Do read (basically everything) each can.
Best as I remember some dosen't do well out of contact with the water.
Some may be more suited to in and of the water like your describing.
Seems that certain ones want the hull to be sanded with 40 while others just want a deglossing to stick.
Redid a skiff a couple of weeks ago and found that barnicals attached to certain paints as did moss.
They removed easily, it was like a film had grown over to allow them to attach.
Weigh out the need for checking the boat so often and keeping batteries up for the bilge amongst the other things to have to worry about a boat being docked for a duration.
I've found here it takes about 14 days for small barnicals to start, if I use the boat frequently they din't seem to have a chance to take hold on an unpainted hull. Although I know they will.