The Fun Finder did great! We were on some very rough forest roads, with big rocks and ruts and mud and sand. No problem. We have the "axle flip" setup for more clearance, and leaf springs, and shocks. And we go really slowly and carefully -- five miles an hour on those dirt roads. No trouble at all.
The other thing is the amazing insulation they build into the trailer -- it was about 33 degrees every night, and never over 45 in the day. The trailer was quite comfortable -- we did not run the heat except at shower time in the evening. Otherwise, our body heat kept the trailer at about 55 or so, which is just fine with enough warm clothing. At night, we would open the bathroom hatch wide, and it would drop to about 40. With a heavy comforter, we slept like hibernating bears.