I incorporated small display storm windows in the doors of my tear,
These little windows were part of a 6 sided point of sale display. Each window had a different feature and were in 6 different colors to show what was available.
I purchased them at an auction of a mom and pop lumber yard closing. I think I paid $5.00 and got 6 windows mounted on a point of sale carrosel ( used it for firewood)
Yeah you caught me.... the green one is the right and the other pics are the left , and yes it is brown. To date none of the camping buds have noticed. While the frames are designed to mount flat on the outside I cut the hole just right to shove them thru from the inside and screwed them tight over a bed of 100% silicone. In this pic you can see the 3 tracks for the upper sash , lower sash , and the screen. All of which are obviously removable. We have a neich that mounts to this hole for an AC unit (window shaker) in the summer and of course this shot of the 14" pot belly stove for the January Shivaree.
I filled the void between the frame and the door with the same silicone and capped with a trim strip.
There are hundreds of these little displays in dusty corners of lumberyards and window shops everywhere you will have to ask around but they are out there some times for free but often for just a few bucks. They are too small to be of value to a homeowner but just right for our little trailers.
Here is the "Room addition " ( neich) for the pot belly stove. Have a similar one for the AC unit also