Welcome, and congrats on finishing!
As for insulation, the gap between inner and outer walls is "dead air" and does act as some insulation all by itself, believe it or not. Also, unless the windows
are double paned or otherwise insulated, they are going to be big holes in your overall "blanket."
No matter what, inside of trailers are warmer than inside of tents...in our experience. Never yet have we woken to a coating of ice on the inside--as we did in our tent-camping days.
I hear you about feeling a little sad the renovations are over...Paul wants that Scamp
that was rear-ended and is available in Oregon (or was...) so badly he can hardly stand it!
I shake my head...dunno 'bout another project of that size!