If you are using an external strongback, you will be dealing with slightly different issues, particularly with re-alignment of your forms after you remove your hull. With an external strongback, you will presumably have to re-attach your form supports on the hull side of your forms, which would mean starting the alignment process more or less from scratch.

I use only an 'external' strongback for my builds, and there's no problem with the forms, which stay inside the hull until they are no longer needed. After the hull is glassed on the outside, I fire a couple of staples into each form at the sheer, and sometimes use a small wood block and hot glue to anchor each form at the keel line.
Then the forms are unscrewed (unbolted?) from the supports and the hull is turned over, with the forms inside, and put into a couple of cradle-shaped supports.
Then the deck stripping proceeds.
Then deck glassing.
Then separation, form removal, and glassing of the insides.

You can see a couple of forms peeking through the back deck in this picture: