Since I don't have a van to play with yet.......
I removed the 1/8" plywood headliner and re-attached the canvas to the top using thin (5mm) plywood strips ripped from a 4'x4' sheet from Lowes.
This will allow much easier access to the underside of the top for wiring mods, leak repair, etc without having the canvas falling down.
I used the removed headliner panels as a pattern for the screw holes in the strips. The strips are in the same holes as the headliner around the perimeter of the roof.
Using the headliner panel as a template
strips screwed in holding up the canvas
This is what the underside of the top looks like......reflectix removed
My plans for further top mods are (in no particular order):
Install Yakima tracks
Install a solar panel; poke a hole in top and add connector
Fabricate new headliner panels and cover with padded headliner material
Replace fluorescent fixtures with LED fixtures
Replace edge trim on top (already ordered replacement trim and roof tape from SMB)
Replace high mounted stop lamp (ordered new one from SMB)...the old one is serviceable but a new one was $12....
Sleeve crossbars with cro-mo tubing and rework pivots with shoulder screws, etc.
add additional reflectix under top
prime and paint top van color (need a van first!)