The width is 50 some inches but the wheel wells are there so you may need some 2x4 or something to keep plywood from flexing over them. And the length of the bed isn’t near 8 feet so you’d need the bed open and the boards strapped in.
Your other question is about.. bed vibes? That's not a real spec (for any truck builder). You can put a 100x4 sheet rock in any 4'+ wide bed.. best of luck to the person behind you. Don't forget the red flag (day) or light (at night).. in north america.
(Anyone seen detailed dimensions specs?)