: Does anyone have experience taking a perfectly good stitch and glue and
: modifying into a hybrid?

Most hybrids out there are taken from perfectly good S+G designs. There's
no need to make the deck exactly the same shape as the original S+G had.
My hybrid Cormorant was built with the height of the deck peak the same as
on the original design, but the deck cross-section changed to a perfect half
ellipse to give a bit more room under the deck with no change to the windage.

: Am I crazy to think I can basically cut off the
: deck, build forms and strip the deck?

Sounds eminently reasonable if the deck and hull were joined as in the strip
boats per Nick's book. If there is a sheerclamp, it might be a little more
difficult... But as you are presumably not intending to preserve the deck
for another job, you should be able to cut it off a little above the sheer
and then level down to the sheer with a block plane. Cut through the sheer
clamp so you can remove small sections at a time (and any splitting which might spread into the hull panels would be minimised). Or if you do intend
to reproduce the original deck shape, you could cut the deck above the sheer
clamp and simply plane off the rest off the deck to leave the sheerclamp
untouched and available to secure your new deck.

Stripping a deck over a hull which is already fully glassed is exactly what
I did on my hybrid and when the forms (just hot-glued into the deck) were
removed, the deck was then glassed inside and was no problem to fit to the
hull.

Go for it !

Andy