Greetings all
I just made a set of shelves for my SWB GQ patrol. I need the back seat so this is only a short shelf. I have attached pictures and a basic parts list with the size of the pieces to build the outer frame. Cut the other parts for the inside to suit your own situation. It was all done from a single 1200 x 2400 piece of 12mm construction ply from Mr Plywood - and they cut the pieces to size for me (I only cut the ones on the inside with a hand saw). Cost was $75 for wood cut to size. I matched the paint colour by taking the little plastic screw that holds the jack compartment to the paint shop and they matched the paint colour exactly to match my vinyl. Also, to fix floor in, I used the screw holes for the two tie-down points in the back. To mark the holes, have the screw heads sticking out a bit, place the shelf system in and align, then bash floor with a rubber mallet to mark the points to drill holes. Holes align up perfectly. You need 4 x 6mm x 35mm screws and use 1 inch washers and spring washers to hold floor down (don't skimp on size of washers or the screw head could come through floor if you hit a big hole)
As for the four shelves, I commandeered them from my daughter's bedroom to a higher calling.
I hope this can be of help to somebody. If you have any questions, just shoot them to me.