Small RV definitely has advantages and there are a lot of dirt roads you can go down in 2wd. But I would hate myself if I didn't (or couldn't) take the opportunity to see places like this:
No RV or van (non high clearance 4WD) would or should take roads like this. In a Suburban? No problem. Parts are cheap and plenty as well. If you need stand up room, maybe one of those SUV tents will do. I personally think given this guy's budget and what he wants to do, it'll be hard to beat a Suburban.
This is a very well maintained road that any regular 2wd could handle if the weather is fine. Class B and C RVs go on roads like this all the time.