After doing a bunch of research on the forums the plan is as follows…
I’m going to be using primarily Poly-Iso ridged foam insulation. The panels will be held in place with spray foam (the door and window variety). In the door area, and some of the frame channels I’m going to use 3M Thinsulate which can be pulled into those tight channels and pressed around the door lock actuators etc.
Walls / Ceiling
The Walls and Ceiling will be covered with 6mm Russian birch plywood. The great thing is it comes in 5’x5′ sheets which work great to not have too many seams. The ceiling can be covered from one side to the other with a single sheet spanning 2 ceiling bays.
My van had the factory composite wood floor already installed. With the small size of the van and the fact that much of the floor will be covered with fixtures I’m just going to leave it as is and build on top of that base floor.