Last winter I did something similar to what you propose.
The wood was bedded in polysulfide, or something else that was black and not terribly strong, and wasn't super difficult to separate from the deck. Being careful, moving along slowly, only a few boards split.
The most difficult part was the screws that didn't want to budge, or had their heads split, stripped, etc. In those cases, I used the smallest hole saw that would get around the screw head
and drilled _around_ it. This separated the plank from the seized fastener, which I later removed once the plank was gone. I used a block of hardwood with the same hole cut in it as the guide for the hole saw, since obviously there was no pilot bit (the screw would be in it's way!)
I brought the planks home, cut new rabbets, bored out all the old fastener holes and filled them with teak plugs. Sanded, they looked spectacular.
Back at the boat, I repaired the fiberglass
deck underneath, filled all the old fastener holes in the fiberglass
, slapped on one layer of cloth to really be sure all those filled holes would stay that way, then glued the teak down with Teak Decking Systems FFE-200, which was MUCH easier to trowel on than their FFE-180.
One season later and they are all still where I put them!