WOW!!! Thanks, Travelnutz!! I hadn't considered lining the gas compartments, for example (and I have plenty of Reflectix left). I printed your list and am heading back out to the 5er...
We only have one large pass-through storage area under the bedroom, and it's next to the furnace, so I'm guessing there's some ambient heat coming from that? I bought a wireless weather thermometer, so can check that once we are camping. Yes, there's a plastic corrugated bottom seal under the trailer that I plan to add a little Gorilla Tape to, where there's cutouts for the drain lines. I closed the AC vents - but forgot the AC unit itself - duh!! Baggie over the vent filter - check!
How do you hold the lexan on the windows? Double-sided tape on the frame?
I figure if we could make our 28' Class C with an exposed floor, tight enough to be heated with a single electric heater - then we should be able to do the same with this much-nicer (also 28') 5er.
Regarding the previous post: there's something magical about RV's - they take us to wonderful places where great memories are made. I totally understand how hard it is to part with one - we haven't let the Class C go, even if it only gets used a handful of times each year. At some point, we'll probably figure out which RV will work the best for us; and let the C go...and yes, I'll shed a few tears about that.....