: How about making 3-5 (or whatever number to help it hold it's
: shape) top-half form duplicates spread over the length, tacked
: into the deck with hot glue, and used to set on horses while
: coating?

I don't think this is a good idea: it will maintain the shape of the forms at those stations but it won't do anything to keep the deck/hull from twisting or sagging. Forms without a strongback can't do their job. More importantly, the deck/hull aren't usually anywhere near strong enough to remove from the forms without glass on one side.
As a previous poster said, it is best to keep everything on the forms and glass the deck and hull in two steps. When you have glassed both, take one off the forms and do the inside. That will take a while when it comes to the deck because you probably have to do hatches and maybe other stuff. Meanwhile you want the hull still on the forms and staying just the right shape to join to the deck when you are ready. Spending a bit more time and avoiding having to fight to join together a hull and deck that don't match up nicely is worth the trouble.

Ric