Good morning, Jode~
I'm never sure how to caulk the bottom on old vessels that will be glassed. My concern is always about water making its way into the seams from inside the boat. I suppose as long as the cotton+paint is tight all will be fine. My Dad 'glassed his Great South Bay Scooter in 1954. Although I have rehabbed portions of the skin, I've never had to remove any big portion of it. He told me he saturated the seams with linseed oil.
Also, I suppose if you'll be oiling annually, that'll provide ample insurance.
All the best,
SJS