Thanks @Lilnuts2 .
I came here to post a quick update on usage. After several months of having these installed, I'm noticing the need for some solution to hold them flush against the window (to minimize condensation). My set was originally held in place by the vertical components of all of the seat belts in the 15-passenger, but after removing each of those over time, the covers tend to hang straight down.
Velcro hasn't worked for me, though that would be simplest for those who could sew the curtain-side of the velcro onto the curtain. This product has an almost clear side you could use on the window:
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
I'm really happy with the magnet solution I provided for the rear two windows, so I'm going to be personally retrofitting the other windows similarly. The big challenges will be my sewing skills (and for those who've tried, sewing a magnet into a hem in particular is a pain b/c the magnet sticks to the machine) and getting the matching magnets behind the trim pieces, since various interior upgrades have been built on top of the trim panels throughout.
Anyways, wanted to share that. Camping in 36 degree weather was challenging this weekend. The family didn't love the Webasto-style gas-powered heater cycling (and it eventually ran the dual 12v deep cycles below the min voltage for the heater, but that'll be a dif thread), and there was quite a bit of gap between the covers and the glass. For Ray or whoever takes up the mantle of this project, incorporating perimeter magnets in the production process would probably be worth it.