My efforts to shelve this have failed miserably.
Actually, I only contacted one "seller": the local van with the rusty bumper has been re-listed, twice, so I contacted them through both ads, and they ignored me completely.
Instead, I've been rethinking the big picture.
I'm leaning pretty strongly away from truck campers: my area is not very RV friendly in general, and I think truck campers are just too obvious. Also, I don't think I've seen a single truck camper in my area in months, and I drive a lot. As a secondary concern, Super Duty pickups get pretty bad mileage even without a ton (literally) of added weight in the bed. So they're in kind of the "dream garage" for now. I also remembered a highly unusual type of camper: they weren't sold in the US, so it's not a practical solution for now. But maybe once I get settled into my first rig.
Now pulling in the direction away from stealth, I also kind of want something which will allow me to have company sometimes. And while I am aware of about five YouTube couples who live in low-top conversion vans, usually that was a joint decision by a long-term couple. Meeting someone new, I think there are a lot more girls willing to visit a well-equipped Class B than a rustic and spartan van.
Tying it all together, I just ran across this tour on YouTube.
A few things I noticed:
1) Young people in Austin now sound like they're from the Midwest (I noticed this a couple of weeks ago briefly hearing NPR interview the band "Wild Child")
2) A regular-duty van (E-150) appears overloaded even with a lightweight build (lithium batteries, only 6 gallons of water, no plumbing). But high gross weight conversion vans basically don't exist.
3) They spent about 500 hours on a fairly minimal build. That's a lot of opportunity cost for me, and it is nonrecoverable, unlike the extra cost of a commercial RV
So I seem to be leaning toward a commercial Class B: even though they are not designed for tall people, full-timing, or four-season operation, it will probably still be easier and more reversible for me to start with something that almost works and modify the systems as needed.
I also learned that the IRS mortgage interest deduction can be applied to two dwellings, and an RV with cooking, sleeping, and toilet facilities qualifies.
So I guess that narrows things down a little. I still need to tour one and figure out which length to get.