Any details on the support system for your platform? I'm interested!
You bet!
I have the bed kit, so the rails made this super easy. They became the supports for my sides. I didn't have this in my Tacoma so had to built a support system.
Two sheets of plywood (you'll have extra).
Cut the plywood first to 66.5 inches for the width, then cut straight in half (so I had 3 2 foot x 66.5 strips). Then I cut them in half (in my Tacoma I used one long strip, but with this bed rail method, a single sheet won't fit). A benefit to this, however, is it's easy to lift a pane in the back to get to gear underneath.
I then trimmed each piece to match the contour of the truck down the bed. For the two pieces up against the cab, I also had to trim a bit on edges so it would fit snug. It took a few trips back and forth from the saw to the truck to get it right.
I bought thin carpet and carpet padding and glued and stapled each piece of plywood. Mark the back of each panel so you'll know exactly where it goes when you remove and reinstall.
Cut a 2x6 to run the length from the cab to the tailgate. Make sure you check the height, there is a edge on the cab and if you measure too high, you'll cut your 2x6 too short. Yup. I speak from experience. I also put some carpet on the ends of the 2x6 so they wouldn't scratch things up.
Deciding on the supports was a tough one. In the end, I went with the same solution I had in my tacoma. Three of these:
https://smile.amazon.com/gp/product/B0024E6ZW2/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
The problem is they can't quite get long enough. So I cut 4 small 2x6 squares. I then screwed the supports and legs to the 2x6. In my Tacoma I had the bed so I could use two different heights, don't really need that here but these adjustable legs still seemed to be my best option.
I then screwed down a small length of wood on each panel to keep the center support from sliding around (you can see this in my included pic).
If you barrel down a super bumpy road, the panels can bounce up and not fall perfectly back into place. A simple strap underneath would stop this. I only ever had that happen once in the Tacoma though. Most of my driving is pretty tame. I haven't added a strap yet, but I probably will. I also never had any issues with the support structure, and there were times I loaded a lot of weight on the top of the bed. The center support is sturdy and stayed in place like it was supposed to!
I designed it for sleeping and thought I would remove it unless I was going on a trip. Turns out, I like it in all the time. I generally have a memory foam pad and sleeping bags laid out in back. I can store stuff underneath and feel better about security. Also have some simple velcro curtains for the windows when I'm spending the night in a rest area and want some privacy.
The bed rug helps with insulation, and when I have to crawl up under the bed to pack or unpack gear....