I am building a M8A1 Ammo Mule style trailer. It has ez lube 3,500 lb brake axle, 3” axle tube, 6,000 lb leafs, rectangular box steel frame 1.5” x 3” x 16 ga, 18 ga cold roll smooth sheet metal, 26” side walls, lid with external adjustable tent rack, spare tire mount, rear leveling jacks, side...