If my bed didn't have rust holes the size of my fist in it, I would cut out the back of the cab and bolt it to the bed like that. Run a couple seats back there or something. I like it 
Heck if you were closer I'd give you a sweet second gen bed rather than scrapping it.
You need to drop the floor of the bed down a few inches or the rear passengers will be staring at the back edge of the roof..
