Hi Bluerunner - welcome to the forum.
Definitely some good input here so far. Looks like you already have quite a lot invested in improvements for the 4runner. The SAS would definitely add to the strength and fun-factor of the truck. The ride and efficiency could improve or suffer depending on a lot of variables. I have thought about a SAS for my own truck, but decided against it for the time being. I put some of my thoughts on the subject
here (about half way down the page). Since writing that article, I am 99% sure I won't ever do it with my current truck.
Scott mentioned testing modifications prior to a trip (a rule that I am very much guilty of violating quite often

)...
In a similar way, I would suggest testing your mode of "living" while out on a trip. Do a "test trip" or two. Robbie is correct - people can tend to go overkill and bring everything under the sun. If you have ever been a backpacker, you can more easily relate to this. My wife and I spent 4 months on the Baja peninsula living out of our Tacoma. We could stay "out there" in the boonies for up to two weeks at a time with water and fuel being the limitation in most cases. If you think about how a backpacker can get by for weeks/months with only a backpack and some occassional stops in towns to resupply consumables, the thought of having a small truck with a 6' camper bed seems luxurious. Since that trip, I have done lots more expedition trips and weekend trips, and have refined the ammenities and capability of the truck a bit. But the first "test runs" will teach you a lot about what you keep, what you get rid of, and what you need to add. Nowadays I have a fridge and an elec. shower, and other stuff... but I know where I started out, and what basics I really need (the core stuff) and that has allowed me to evaluate the "fancy" stuff I have added in a much more effective way - I think anyway.