I cut and fitted the 3/4" plywood first. I also took a router and rounded the edges over so that the fiberglass cloth would form to it. The floor in the front was the first I removed and the ridge left from the old fiberglass was the guide for fitting.
I bought 6 1/2 oz. cloth and epoxy resin on ebay and the cost was not too bad for the protection.
When it was time to reinstall I cut strips from the cloth and layed up the bonding to the shell. The hardest part was fitting the wall in front of the door to get the door opening square.
I also bonded in 1/2" plywood bulkheads that make up the new front bathroom area.
I did not fiberglass these bulkheads overall.
On later bulkheads I bonded them in with polyurethane sealant/glue.
All of the floors are fiberglassed and bonded with that same glue to the frame. I also added frame work to the edge of the shell for greater strength overall. The plywood was affixed with screws closer than originally along with the bonding.
While working on the rest of the trailer I had leaking windows
and the water pooled up on the floor, but none penetrated the fiberglass into the wood.
I layed down 1/4" cork underlayment over the floor (attached with the 3M spray adhesive). Under the bed I used some carpet and the walkspace I used vinyl laminate "wood" planks with adhesive tabs.
All in all I am happy with the way it turned out.
Connie wanted a camper with out bugs and creepy crawlies. Toward this end I filled in all of the vents etc for refrigerators and heaters etc. Lots of fiberglass work.