Are you in Slippery Rock Pa.?
I had" Troy Ridge " out of Millersburg Oh. build me a custom flatbed with removable top boxes. All aluminum. The flatbed is made of 1/8 in.. with builtin bottom boxes. Bed weighs 535#. 2 custom top boxes weigh about 90# apiece.
Millersburg is not far from Slippery Rock.
I'm very satisfied with the quality. and the price. Troy Ridge builds about all the service boxes for the Amish construction business around Holmes Co. Ohio.
Might be worth the drive over to talk to and see their facilities.