Update: On my RV Building Plans....

re: insulation. I don't know if it's been said or not, but you mentioned spray foam insulation. While it has it's place, I would not go with that. If you have never seen the performance of real wool insulation, I suggest you look at Good Shepherd insulation. I have used this in parts of my log home construction. I only wish I had found out about it sooner. It's all natural, effective, and safe. Not sure we can say that about foam or fiberglass batt. I've left this stuff out in the rain as an experiment, and it doesn't turn to slop. It just sits there laughing at the water. Doesn't change one iota! Yes, it's more expensive, but if you develope a leak or condensation, it will keep it's insulating properties and not slump out of position. It will dry naturally and remain in place doing it's job. Every trailer should use this.