Make it three recommendations to get a van.
I've owned several and all have been driven extensively around the country in a variety of scenarios and environments. I believe you can get a good one,
and outfit it the way you want, for under 30K.
My first diesel van, a well-used '98 Chevy Express long-wheelbase and former delivery van, cost me only $2700.00 (not 27,000). I put around 300,000 miles on it. I lived out of it and drove the piss out of it all over the US for more than eight years, mostly highway. It had over 500,000 miles when I retired it.
I've had my current van, an '08 GMC Savana, also diesel, since mid 2011 and have driven it all over North America too, from the coast of Maine to California and northern Quebec to the Mexican border. It cost more like $20,000 and was in like new shape.
My suggestion would be to get AWD or 4wd IF you can but to not get too hung up on it. None of my vans, including the two most recent, had 4wd. My current van has taken me everywhere I've wanted to go, even towing an off-road trailer (which is 3500 GVW), from Padre Island beaches on the Gulf of Mexico (got stuck in an old buried soft-sand firepit, got myself out) to 62 days straight of being aired down for back country along the Mexican border (literally hundreds of miles of gravel and rocky roads, not stuck once). Having, and being used to, a
limited slip rear end (positraction) can overcome a lot of, not all, situations.
I would also suggest not to go too strong on re-fitting the interior with permanent built-ins if you're going to be doing a lot of different activities over the course of your travels. I've had vans I've built in cupboards, extensive storage, counter and sink, pull out desk, etc and over the years have let my van interiors evolve to a much more simple, functional, and multi-purpose design. Images below.
I'll leave type of van, and whether gas or diesel, or hightop or not, up to you, though have definite thoughts on brands and engine, too, if you want more info.
Interior last year.
Current interior
Loaded up and rolling