22' travel trailer rebuild from the frame up - NEED HELP!

All Rv's have a frame of some sort, even if that is a composite panel. Wiring and plumbing need a place to go and most have windows.

The wood framing in my Starcraft was just conventional platform framing, 16" OC. I'd bet the OP has similar, not that it matters if he's building out new walls. One trick might be to increase the wall dimension by 1/2"-> 1". That would make a big difference for insulation. If using the original windows, it may be nixed, though.