This is a great read so far.
I'm in a similar scenario as you with an LX470 slightly modified and ab to click over 200k. I need a daily driver for my commute 60 mi x 4 days a week. But want to dual.purpose my commuter as a road trip car camping machine.
For the same reasons you describe I'm leaning toward a Toyota hybrid. The appeal.of having AC and heat will really extend the camping season for my 7yo son and I to do more hiking and camping. The RX450h or Rav4 hybrid are on my radar. Initially I was tempted to go with a Prius V but the low ground clearance has me worried... I looked under a prius V and the 5.9 inches of clearance and sensitive parts too easy to bash into a tree branch or rocks. And to a lesser extent the lack of AWD, but my understanding is that toyota hybrid AWD is a bit of a farce relative to Toyotas typical 4wd and honestly it seems that the world of AWD on unibody toyotas seems to be lacking when compared to subarus and, less so, Hondas AWD. And the hybrid RW electric motor even less effective. It just doesn't seem.to be very well executed with the rear electric motor with such limited power and no power sharing differential to limit slippage between the back wheels, sounds like basically an open diff and no trac system to effectively limit wheel spin to redirect the power to the wheel with traction. It's too bad, but still it is likely better than FWD only... sometimes all you need is that little nudge to get the driving wheels onto that bit of grip to pull you through.
I'm not very familiar with the 3.3 or the 3.5 v6 engines. Are they about the same reliability between the two engine series? Any.pointers when looking at the various model years of the RX hybrid? I'm aiming for the most recent and/or lowest miles for $12-15k, ideally toward the low end. I'm hoping I can find one under 100k and 8 years so.it will still.have the hybrid system warranty in case the battery or genset have issues. Hybrids are very new to me, makes and a little nervous not being able.to diagnosed and fix potential.problems without paying someone.
Good luck with build. Keep the reports coming, I think I'll be treading the same.path in the next few weeks.
RE: tires, I recently installed Cooper AT3 XLT 285/75 on my LX. I've really been pleased so far. They've done extremely well in the recent hurricane and stormy downpours, recent snow storm, and general daily commutes. Of course as the tire wears and the softer outter compound gives way to the denser/harder inner layers the tires characteristics will likely change. How else can they put up a 60k mile warranty AND have great attributes... like Blizzak tires that are great snow tires until 50% tread is gone, then you basically have all season tires.
Why 17" rims? I would think 16" rims would alow for more rubber, better to air down when needed, better ride compliance over all for the gravel and dirt?
I love the lx470s, so much you can do with those. You mention that you are considering the rav4 hybrid and rx450h but I would recommend checking out the highlander hybrid as well.
To answer a few of your questions, the 3.3l engine was used in the rx330, rx400h, es330, Toyota sienna, and Toyota highlander/hybrid, and it was the optional engine in the camry for a couple of years. Pretty reliable overall, and the highlander hybrid used it until 2010. The 3.5 which the rx450h is based around has been in use in Toyota vehicles since 2004 (avalon) up through 2018 (still avalon) but was found in rav4, camry, es/rx350, highlander (2011 model year for hybrid), and rx450h (2010 first year). The hybrid variants were tuned down it seems and lost about 20hp, likely for economy. They also use a slightly different engine code based on the 2gr-fe, 2gr-fxe for hybrids. That being said, it's a great engine as you can imagine based on how much Toyota used it.
Regarding the hybrid awd system, as far as I know the rear motor in the rx400h, highlander hybrid, rx450h, and rav4 hybrid are all very similar and all rated at 67hp (95-103 ft lbs) dedicated to the rear wheels. That being said, you cannot lock the rear drive on, it is a system that activates when high load or slip is detected. I honestly don't think the rear tires will ever slip unless on the slickest of surfaces, there just isn't enough power when you factor in the weight of the battery sitting over them as well. It is more of a push to assist the front. You get the extra power from the rear when going wide open throttle as well, say on a highway on ramp, so the additional power is welcome in situations other than ones where 4 wheel traction is the main objective.
The front hybrid motor appears the same or similar for rx based hybrids and highlander hybrids across the years as well. Rx400h and rx450h both use a 165hp front motor (245-247ft lbs).
I'm really liking the cooper's and we will see how they do in the years to come. Haven't had a good enough snow here to test them out (as well as the awd system) but they're great in the rain and surprising how quiet they are. The reason I went 17" was there were a few reports on forums that 16 would not clear the brake calipers. I'm not entirely sure if that's accurate, but I got a good deal on the 17s and was able to get a decent tire that fit.
And for my personal vehicle, with the heat OFF, heated seats ON, nothing else on (car ON obviously), the gas engine runs 8 minutes per hour to recharge the hybrid battery. So with heated seats, and the cars computers maintaining standby, you get 52 minutes before the battery needs to refill (down to 2 bars, up to 6). I think with a sleeping bag on top of the seats folded flat if you are under 5'8" you can sleep this way comfortably and warm, much like a heated blanket (also an option to get a 12v heated blanket). If the heat is on, this will occur more frequently, as the heat is still produced by the engine and goes through a heater core. It is best to run the heat on recirculating so you aren't running cold air through the system. In essence, the heater core is a radiator, so as you run the heat, you are cooling the engine. By running on recirculating, you are reducing how much cold air runs through the heater core, cooling the engine more slowly, reducing the frequency of which the engine must run to maintain the set temperature. The lowest you can set the climate control to is 65 degrees for heat (below 65 is called "LO" which I assume is just outside air temp).
I have not tested the AC time, but the AC is electrically driven, so the gas engine will only need to run when the battery is down to 2 bars to charge up to 6 bars. The frequency will depend on the temperature you set, so if its 90F outside and you set AC to 80F, it won't drain the battery nearly as much as if you set ac to 70F. Though depending where you are, you may not need AC at all at night.
The other nice thing is being able to use and charge electronics if you have an inverter. The 2 15A circuits that power the 12v sockets can supply 360w across 3 sockets, so given inverter efficiency of ~80%, figure 275W comfortably. Enough for a laptop, tablets, phones, tool battery chargers, really depends on your needs.
SORRY for the long post!