Big long trailers would not be my cup of tea. We camp back off the trails alot here on the East side of the USA.
My OFF-ROAD POPUP setup has all the comforts of home just not alot of inside move around room. This makes us live more outside which is what we like to do anyway...
The one post above mentioned the Smoky Mtns Natl Park - I was driving thru there with just my truck on one trip and came up on a fridge cover laying on the side of the road just after going around a low overhang rock on a blind curve. Throwed it in the back of my truck... Alittle bit farther down the road I came up on a mangled up BAT WING antenna. throwed that in the back of the truck as well. Then I came up on a big 5th wheel trailer sitting in a pull out with the owner walking around it. I stopped and said you looking for these haha... Sure enough they belonged to him... We had some good ole fresh made bean coffee and went on our way...
I have always thought the 24-26 foot length would be the perfect maximun length I would like to play with. Low cost maintenance, better gas mileage, ease of travel are a few things I would think about...
Its all about what you want to do and put up with I reckon... We are off trail tent campers since the early 60s... never really grew out of that..
For us bigger is not necessarily better...
Roy Ken