I have an old box trailer that used to be on a straight truck. the box is about 20 foot long, 10 eight foot wide and about 9 foot tall. the old door on it is shot. It is a very thick, heavy door. I can reuse the hardware after cutting off the bolts and replacing them.... but I need info on rebuilding the door. What I am thinking is laminating a few sheets of ply.... on the outside, treated 1/2 inch, in the middle 3/4 OSB, and on the inside 1/2 ply. would be I think 11 10inch sections. I would have to tongue and groove them on the top and bottom of each section.... thinking cutting each sheet into sections, lining up with t&g already there and gluing and screwing them so I would not have to actually route t&g into them.