[Andreas Macke]

It seems like polyiso attached to walls/ceiling, with a bread of Great Stuff around the polyiso, and covered with thin luan/ply is a popular path to a low-fuss build. Has anyone here experimented with gluing the polyiso to the panels instead?

Probably a little more fiddly, and you'd miss out on the gap filling with Great Stuff around the perimeter on the polyiso - but it would allow restoring the van to original condition very easily. Anyone have direct experience that suggests that would or wouldn't work?

 

[keeponvaning]

No need at all to use anything but friction to keep the polyiso in place!

 

[JohnnyRambles]

The problem with this approach is gluing the paneling to the foam makes it far more rigid. The roof and the walls are not flat, but have a noticeable curve to them. With rigid panels you'll have increased difficulty getting them to fit well.