After seeing prices on back seat setups, decided to build my own. Wanting storage incorporated as well in the  base I built a wooden 2X10 frame, plywood bottom and lid. Lid is reinforced with aluminum angle, and fixed with heavy duty gate hinges, and some compression lock latches. Sealed the lid with some self stick refrigerator type rubber gasket, to keep out dust and water. Coated it all with some spray on truck bed liner, which sealed the wood well and gave it a much less slippery surface.

The box attaches to the bed for easy removal, with some fabricated slide in front connections, and some small turnbuckles in the rear to lock it in place. The seat then fastens to the box lid in similar fashion, secure but quickly and easily removable from the box. The seat is a WISE folding bench seat, ($160.00) a little weak with a 1/2 " plywood bottom and back, but easily bolstered with some extra plywood. All made for under about $300.00.

Planned to finish it off is a roll cage addition, (which will also help support the seat back) with quick disconnects to the existing roll bar for tilting the bed, and a soft top on the cage add on for a cover, and seat belts.

Looks good nice job

Watch the weight limit on the bed.  The frame is cheap steel and bends easily.  I got crucified on Facebook for having a seat in my bed and the bed bending "from the weight of my two teenagers".  I took the bed apart and reinforced the frame with additional metal bracing. 

Watch the weight limit on the bed.  The frame is cheap steel and bends easily.  I got crucified on Facebook for having a seat in my bed and the bed bending "from the weight of my two teenagers".  I took the bed apart and reinforced the frame with additional metal bracing.

Yah, I probably should look into reinforcing it a bit, it is a little weak looking under there..