Unlike Transit and VW my van didn't have panels behind the ply lining, this video shows how I make templates to then cut out of 5.5mm ply to make panels to then be carpet lined
Print bord is a better solution and thin aluplateis even much better, in "Volvo Laplander Camper" walls are in 3mm printboard camperdoor and cabine door are in thin aluplate 1,5mm so they not can be damage off water or moist. If i should build new camper today I probebly use alu on all place it isolite and also reflect back your heat and also in summer keep heat out. I have also a camper /housboat all build in alu and that stay cold inside in hot summer so alu is very effectiv.
