Our TD was finished in 2004 (but we snuck it out for a couple of trips before it was completely finished). Last month we took it to Baja Mexico for a fishing trip (mostly but not all paved roads). We just got back yesterday from a 2,000 mile trip to Idaho to see the total solar eclipse of 2017. Again mostly highway, but we did a fair amount of dirt roads too, including some dirt roads that were badly rutted & rarely used.
The wooden construction is holding up well, but I do see some minor buckling in the thin oak sheets that cover the inside walls & doors, and galley counter top. That might have something to do with the varnish. I'm not sure why it does that.
We covered the outside completely with aluminum; top, sides & bottom, which probably helps a lot. We store the TD outside, uncovered, in mostly dry Southern Calif. Our TD was constructed of 1" plywood without a frame, I mean, the trailer itself has a 2" square tube metal frame, but the cabin is all wood covered by aluminum sheet metal.
I would strongly recommend against anyone ever putting screws into the ends of plywood. None of those have held. Instead, use a wood (consider using a hard wood such as poplar or red oak) or metal 1"x1" in the corner and fasten both panels to that. Glue & Screw. Protect any exposed wood, especially the ends. As you construct, think about how it can be repairable. Our TD cabin was not designed to be removed from the metal trailer frame. The plywood side panels extend down to cover the trailer frame and are bolted sideways into the trailer frame. Those bolts are about 4 or 5" long, and some have broken. They are a real pain to replace because there is no way to get to the bolt head, which is counter-sunk & covered by the aluminum sheet. I had to probe around, drilling small holes through the aluminum skin to locate the bolt head, then drill a hole big enough to extract the broken bolt. (then patch & waterproof it) I replaced those with thicker grade 5 or grade 8 bolts so they probably will not break again. There are 6 or 8 of those bolts and I plan to replace them all before the rest of them break too. Even though the trailer was "finished" I have done a number of modifications & improvements, which necessitated taking things apart a bit. For example, when I added a fridge, I had to move the bulkhead a few inches.
https://td.roughwheelers.com/2015/solar-fridge-project When I looked under the TD last year, I could see the naked bottom edge of the side panel plywood. It was not looking great, so since the weather was dry, it was a good time to seal that exposed plywood edge with Henry's roofing tar. It took forever for that tar to dry... like weeks because I globbed it on so thick it slowly dripped off. I also used some clear silicone to protect & seal other similar parts. When it rains, we have no leaks. We have driven through knee-deep water. Every screw hole through the skin got a dab of silicone sealer before being tightened. I'm sure that helps longevity a lot too.
Overall, the wooden construction is holding up well, especially in light of how hard we use it and the offroad trails we take it on.
![150767](http://tnttt.com/gallery/image.php?mode=thumbnail&image_id=150767)
![150766](http://tnttt.com/gallery/image.php?mode=thumbnail&image_id=150766)
![150768](http://tnttt.com/gallery/image.php?mode=thumbnail&image_id=150768)