Paid for the aluminium bed on Friday, otherwise I might’ve been interested in your line on a bed and tailgate. I ultimately decided to go with the aluminium bed because of weight savings and cost.
As for fiberglass, this is who I got the cab and fenders from, they also make a bed and are located in Goderich. Very solid pieces but fitment and mounting is all on you and if it’s like the cab, you have to figure out how to mount the hooks and latches with bolts in place of spot welds. http://www.gozzardcomposites.com/
My original far too rough to take moulds from, lots of dents, rust holes, and one bed side is crumpled along the wheel well. I have don’t have the time, tools, or the skill to do the work it needs but it could totally be repaired by someone who does.