You can still buy Ensolite foam, by the way, so you could get new foam of the same thickness, and glue it on the the walls where you are missing yours.
I would want to cut the intact foam back and just generally make the edges square, regular, and inconspicuous as possible*. That would probably mean trimming some of what is still on there. Like say, back to the window rubber, and maybe down to an area behind the bench or sofa back. Then you would need to sand off any remaining glue remnants to a nice, clean and fair surface, and then prep with acetone or the like. Then you could glue in the new stuff.
Now, what we *haven't* been able to find is the Ensolite foam with the whitish vinyl layer bonded to one side (which makes the walls of the trailer white). However, you can paint the "raw" Ensolite that you can buy, and you could of course try to match the color.
IR Foam Specialty sells the Ensolite. As far as I know, the original thickness in the Bolers was 3/16", but IR Foam Specialty has a variety of thicknesses, and also different densities. I had them send me a few samples to check them out.
*Or, just go bold, and paint the new foam to look like a Band-aid
Heck, you've earned it!