Buyers Products, at Zoro.com, has cam lock door bolt kits, you supply the 3/4” pipe.
The hinges on Semitrailer swing doors will allow the door to be flat against the side, and a door holder will keep it there.
Penz makes the hinges.
The RV people know all about door holders.
Semitrailer swing doors are PlyMetal (3/4” plywood with external metal skin) or Composite, a metal/wood/metal sandwich.
Plymetal are about $150 each.
Trim to fit, unless you need 49” by 110”.
The external gasket comes in 14 ft lengths, you’ll need a few. They slip over the edge and glue on.
Find a friendly parts guy at the local semitrailer repair shop, hopefully they won’t specialize in roll up doors. Ask them. They’ll have door holders also.
If you want windows…
That gasket holding the window is known as “self locking gasket”, or “universal weatherstrip”
Here’s the one to fit the 3/4” PlyMetal door:
I suggest 12” round tempered glass, here’s some crazy cheap ones:
Scrape off the rubber feet.