Further thoughts:
1. One advantage of 2-at-the-back 6x6 variant is that it enables use of a relatively simple and lightweight detachable tracks:
http://www.prowlertracks.com/over-the-tire-tracks/
http://www.bobcat.com/attachments/steel_tracks
2. Bio, I thought you may find it interesting, an RV sketch with segmented window:
Obviously very different from what you want, but may be an inspiration.
Source:
http://ecomodder.com/forum/showthre...rhome-aerodynamically-13149-8.html#post372611
3. Considering options:
a) small tractor + camper trailer
b) big integrated RV + toad
c) big integrated RV + trailer with toad inside
d) big integrated RV + trailer integrated with toad
e) big integrated RV + trailer integrated with toad, both with a train-like connection
I realized there's also another option:
f) articulated train-like RV with integrated (tractor + trailer) and no toad.
If the tractor is small enough to be used as a city vehicle, there's no need for a toad and you drop whole lot of complexity compared with options d) and e)
However, if you were to push the total size, you would end up with significant length differences between the tractor and the trailer.
Equal length advantages:
* with equal wheel setup, you get the same approach, departure, break-over angles
* if you got weight distribution right, there would be equal lever at the front and at the end
* it's easier to split weight precisely in half
* lowest turning radius at the given length
Also, f) would have to put the generator in the tractor which looses the advantage that on a trailer it's clearly just a generator and on a car it may be considered an engine. Still, it's the most space-efficient variant (in term of camper-usable volume per total length) that includes a smaller car that I see.