Here's an idea of what I did.
As you may be able to see.
Made the frame from 40mm box.
Roof is colorbond.
Sail channel on edges and canvas canopy made to suit.
I have ladder brackets ( roof racks ) added from same 40mm box.
Perspex window in front.
The sides have zips...I'll try to find pick of them. Plastic zips. Use Slipicone or Silicone spray to keep them free.
Also had fluros inside... but these days LEDs are better, with the box you see has switches and also a double lighter socket for compressor, spot lights etc. I ended up haveg second battery in back ( due to snorkel fitted made no room for battery under bonnet. )
You can also see small flood light at rear top. I have two of these for ease of seeing boat ramps ( and boat ) at night.
more later.
LP