It would be amazing to put together something like that.
Here's my parents' rig:
I was 7 when we went with my parents and grandparents to California to pick it up from the Odyssey factory. It's an '88 on an '87 chassis with the 22R-E and 4-speed manual transmission. We sleep 5 in it and occasionally 6. The Toyota RV's were made from the late 70's to the early 90's in the US.
http://www.toyotamotorhomes.com/
The frame and drive train have been excellent...only replacements have been the exhaust system, drive shaft (worn U-joints) and brakes. The engine's only had oil/filter/battery/spark plug changes.
The camper body has been pretty good but there have been some issues with roof leaks and some side-panel rot in one place that hasn't been addressed yet.
The frame is extended in front of and behind the rear axle for this size camper body (~22-foot total length). It has an 8", full-floating dually rear axle with about 7-leaf spring packs (spring-under).
Nearly all of these campers have extended wheelbases so they wouldn't fit right on a Tacoma or Tundra chassis without frame lengthening...with the exception of the Chinook, as pictured in the above post. These larger camper bodies might be difficult to transfer--they're plywood/fiberglass construction and they might not survive the swap. Also, as you mentioned, the resale value on them is still quite high. They're also heavy--I think it would be too much for the stock, semi-float axle and single rear wheels. You might be better off removing the bed from a Tacoma and building your own, smaller camper body using the original wheelbase, somewhat along the lines of the Supercamper.
http://thesupercamper.blogspot.com/search?updated-max=2010-01-06T06:32:00-08:00&max-results=3
It would be incredible to see some campers based on newer Toyotas though. The RV market in the US is very limited for fuel-efficient choices. Only the Mercedes/Freightliner Sprinter chassis delivers fuel economy rivaling these import class-C chassis, and they are prohibitively expensive.
Eric