I’m still waiting for my GFC but built this in anticipation:
This one has a full flat surface & two wheeled bins inside it that are 4’ long 47L Sterilite and 2 - 1’ long 14L Sterilite bins on the end. Bins are carried by Walmart. Built with not quite 1.5 sheets of 3/4 pressure treated T&G plywood ( sq ft wise its 80 % of 1 sheet), 3 pressure treated 1×4’s, 8 galvanized steel braces, 40 screws.
The frame is boards that sit in the pockets built into the box, there are boards used for support in the middle. Cut to perfect length so the bins don’t move around. The door in the back slides in place between the plywood floor and the frame of the box.
I put D-rings where needed and coated it with bed liner.
Weight of platform is roughly 72 lbs according to my rough estimates. You can lose at least 20 lbs by going with 1/2" thick lesser grade plywood. In 3/4" plywood variation it easily supports on rough roads a Arctic Cat Thundercat ATV ~ 700 lbs. Its secure with the locking tailgate, holds all my camping gear on one side, recovery gear, parts & tools etc in a 47 L on the other side. 14 L for dry stuff. 60 L ARB fridge in backseat .
Backpacking type Camp chairs, tarps, tarp poles and camp table in the middle between the braces. Axe, saw and shovel are attached to the slide in door. It uses almost every inch of available space.
The last 13" closest to the cab is a T&G panel…remove it and you can slide in three 20 L military type fuel/water cans, however there is a cost. You lose the 14 L containers on the end…but the fuel cans site as low as possible and does notź block your view out the rear window.
I’m 5’11" tall and I just barely fit diagnolly in the box. Cost me about $ 150 to build and about 2 hours of time. Allows my truck to still be used as a truck while allowing all my camping gear ready to roll at a moment’s notice.