I recently traveled from the SE region of the US up north to MA....and unexpectedly stayed 3 weeks. BOY WAS IT COLDER UP THERE!
I had to add extra insulation to my setup, and found the quickest way was to use the folding (accordion) window covers strategically. I suspended one as an extra layer on the double doors, used another to add insulation to the paratransit doors, and pretty much hung them across all the windows including the front window.....and for good measure I suspended one across the ceiling just under the hatch (and above the heater).
This helped immensely, I also one as an additional thermal barrier between the cab/living area which already had Wool curtains hanging there.
I am already on a K.I.S.S. set-up mission for some reason, and I'm wondering if anyone else has tried this of reflectix.
Though it might be pricier, two immediate advantage I discovered was:
1 - because they are "accordion" style they are much easier to store; AND
2 - Some come with nice designs on them....this could create a win-win
Walmarts, Heavy-Duty ones ranged in price from $8-12 USD
Advance Auto Parts retails one for $22, that has a felted mat-black with jewels, finish on one side
https://shop.advanceautoparts.com/p/...E&gclsrc=aw.ds
I'm sharing because I found them to be BOTH FUNCTIONAL AND DECORATIVE.