Depending on your budget, marine components are more durable and last longer than most of the RV stuff but they are pricey. Unless you hang in the desert most of the time, the interior will get moisture from many sources. Try to use materials that are hydroscopic and stainless fasteners, they don't cost that much more. Coating your woodwork with a quick coat of marine vanish, inside and out will help prevent moisture from saturating into it and speed drying and spill/leak cleanups. Spending a lot of time and effort in insulation is not the fun part but pays back in a more comfortable and quiet rig that you don't have to run a heater or AC as long. Most RV MFG can't spend the time to do a great insulation job since it can't be seen and won't get much of a return on the cost involved in doing it. ,most of my purchases have been from Marine distributers on the east coast, Amazon and overseas through Ebay. It took me awhile to buy all the components at a reduced price but they are mostly all high end marine.