We've had zero build issues with ours. Only negative I can think of is I'm not a huge fan of the flooring material as it has a bit of a softish texture, but is rough and collects a lot of dirt. You have to scrub it pretty well to get it clean. We put a rug down inside and are really picky about taking shoes off right away which minimizes anything. It would be nice if there was separate lighting over the bed/living area, or if the lights had a red option, but that's all easily solved with inexpensive solutions on your own.
I don't deflate the trailer tores to much unless it's sand. Tow vehicle just depends on terrain type
Depends on how rough it gets but I've taken the trailer tires down to 25 and my truck down to 30 when it gets really rocky, but I'm rolling slow so as to not overheat the tires. I'm running 37s on a heavy Power Wagon with a built out pop-up camper shell. Could I go lower? Probably. But I've not had a need to and it's not worth the risk of damage to me. With the trailer loaded and a full water tank I'm running 45 psi on the highway and get good treadwear and performance.
. I’ve done plenty of stuff in my Subaru with zero issues or complaints that had all the Jeepers doing a double-take. Doesn’t mean there wasn’t a better tool for the job 
That's awesome eatsleep...you have done an awesome job updrading your winne! I think any off road trailer that goes off road needs to have all drawers and doors secured. As far as screws coming loose that is more likely to happen if there is a lot of wood involved. Also like others have said ground clearance and articulating hitch give you soo.. many more options on steep mountain roads. Less then 16" and I would scrape just driving out of my driveway.