Platform is made up of white pine sides 13.5" tall. In the center I routed a 3/4" x 4" dado fom the top edge down on each side and the bulkhead ( a piece of pine 3/4" x 4"x whatever it is long) connects the two uprights and sits flush with the upright's top edge. This leaves about 9" under the bulkhead to allow longer items like camp tables and the like to be put under the platform. It's glued and screwed. On top is a sheet of 1/2" ply. The extensions are the same as are the flip out extension rests. I can slide the whole unit in the back hatch by picking it up over the tailgate striker and easying it in to place. It's held in place in the front by bolts through the seat rails and the pine side have been reinforced with plates on both side to keep the wood from shearing if anything untoward would happen. At the rear are stainless L-brackets that slip under the footman tiedown points in the rear of the cargo area and mount to permament carriage bolts (with large washers) installed in the uprights. Typicially I have four action packers, the roll-top camp table, two Pico campchairs, tool bag, possible bag, axe and shovel under the platform. Clothes go in dry bags on top was well as sleeping bags, sleep pads and pillows. Not to mention the travel cooler which get straped in using the four D-rings spaced on each edge of the platform. When not in use it hangs on the garage wall.