I've got pretty much the same truck as a tow rig. Bought it around 96k miles 2.5 years ago. Looks like you're headed down the right road with things.
I've found fuel filters for < $20, but can't remember for the life of me where I got them from now. If I remember, I'll post up.
A tranny temp gauge is a MUST on these trucks IMO. Even if you're not going to be towing, you'll have a decent load and might be working the truck pretty hard on the trails. I got a nice setup of ISSPRO gauges from Diesel Manor for mine. Looks like the price has gone up a bit, but still a very nice kit. Even though I kept a close eye on my tranny temps and ran synthetic fluid, I still managed to smoke the stock tranny last summer. I tow 7k lbs maybe 3,000 miles a year plus daily driving it another 15-20k miles so I'm not really hard on the truck. I put it in a BTS tranny and am thrilled with it. Also upgraded the tranny cooler to a unit out of the 6.0 trucks.
A couple other things to research and maybe knock out sooner rather than later are the UVCH and CPS. There was a recall on the CPS, but since you've been into the dealer I'm assuming that was already handled. The UVCH is the wiring harness that goes under the valve cover (UVCH = under valve cover harness) and it powers your injectors and glow plugs. These are known to loosen up and your truck will run like crap, and sometimes not even run at all depending on how loose they've gotten.