I haven't caught up on this thread in awhile but I'll summarize some thoughts without trying to quote every one:
You mentioned early on you don't know much about cars, which I'm guessing means you don't do a lot of your own maintenance, so DON'T BUY A SPRINTER! You do not want to own one of these unless A. your girlfriend is a Sprinter mechanic B. You never drive anywhere where you aren't positive a Sprinter mechanic can be seen or C. It's fleet maintained where you just make a phone call. Sprinter bashing? No, I'm really not. I like them and I've put hundreds of thousands of miles on them at work and I've seen the horrors they are capable of for people. Buy a used domestic rig you can build out and learn some basic, simple maintenance on or at the very least go with a Transit with a warranty if you feel you must buy new. I wouldn't.
All this coming from a huge German car fan. I maintain my own or I wouldn't have one. Check out hourly shop rates on anything European and try to find out how easy they are to get serviced in, say, Page Arizona, or Parhump Nevada or Lander, Wy.
Chinooks are awesome but don't have much storage space. I've looked for them on and off forever and 20k is a stretch from my experience. 25-30k is more realistic and good ones are hard to find. They all have the v10 which I don't particularly think you need. Rear door access is a problem for anyone who carries a bike on long trips.
Remember this, you're on a forum with a lot of hardcore van, travel and 4wd junkies. Power is addictive. Most here, me included, have more than we need. 2 V10's currently in my driveway, but I really think you sound like a guy who would benefit best from a 5.4 or 5.3 Chevy, maybe an AWD Chevy if you can find it. Watch out for rusty NE ones.
You mentioned recently that you still weren't sure if you need 4wd. If you aren't SURE you need 4wd then you absolutely don't need 4wd!
There is a lot of good info on this thread too, check it out:
http://www.sportsmobileforum.com/forums/f30/narrowing-down-the-search-18715.html