The expanding foam will push panels apart if not expertly applied so it would not get my vote. We used it to insulate truck bodies but w/o the inner panel in place. It had to be shaved to the proper thickness even with experienced applicators.

1953 Chevy 5-window 3100
In the Stovebolt Gallery
More pix on Picturetrail

Dave
Engine & Driveline Moderator

If you can't make seventy by an easy road, don't go. ~~ Mark Twain