I've actually done exactly this.... I'll post some pics of my setup later. Made a wall and covered it in bed liner. Looks great, BUT I kinda messed up when building the box.
Please check out my post I just posted.
I'm looking to get a design/blueprint made with these same measurements. I'm thinking I can get away with 50" wide but might want to go 19" on the height.
Oxsign, Where did u measure from? With my box currently installed I can't measure from the opening in the cab I just got a rough measurement from the back of the bed by the tailgate.
The dealer, if u can help me out on this project also with some box plans/blueprints it'd be much appreciated. Let me know how much u would charge me for something like this. I'm capable of building this, I just want to make sure I have the right dimensions and want to do it right this time around instead of wasting my time and money again on a subpar box for my subs.