nestork wrote:
Sidestep the problem entirely by not using screws.

Use a black plastic roofing cement or a latex caulk as a glue to glue
the new plywood in. Have a helper apply caulk to the trailer frame
while you apply caulk to the plywood and then drop the plywood into the
trailer frame. Clamp the plywood down to the trailer frame for a few
days while the caulk sets up.

When the time comes to replace that trailer bed, just cut most of the
plywood out with a circular saw or jig saw and then use a pry bar to
separate the remaining plywood from the steel. Then use a paint scraper
to remove most of the old caulk from the steel. (Follow up by cleaning
the remaining acrylic caulk off with MEK or toluene or lacquer thinner
or acetone if desired. Remove the old plastic roofing cement with
mineral spirits.) Otherwise, you can just caulk in another new plywood
trailer bed exactly the same way over the existing caulk.


Sidestep the "problem" now and make it all the more difficult to do again
in the future.

How hard is it to drill a bunch of holes in plywood for carriage bolts?
Been there, done that. Trailer came out quite nice. Both times.