Good luck in your hunt for a trailer, Shay. Lots of options in the 15' or less category.
I have extra insulation on the walls, and dual glazed windows
. We camp more in colder climates, and the extra insulation for us means that the furnace
runs less, minimizing use of the battery
, and is also less noise too.
We don't have A/C yet, and really appreciate the insulation factor when we have travelled to hot climates, as it keeps it cooler longer. If you were in hot climates, and were hooked up to the grid using A/C, the added insulation would not be needed as much, but still nice.