When I first built my PocketShip I debated putting anti-fouling paint on the hull so I could keep it on the water. Now I am glad I decided against it. On several occasions, I have discovered what I will call "stress fractures" on the bottom of the keel. These are small tears that follow the weave of the fiberglass fabric--in other words, the cloth has separated and possibly exposed bare wood. These tears are easy enough to repair, but if I left my boat on the water all the time (and didn't inspect the hull now and then), much greater damage might have ensued. Also, I suppose it is possible to suffer a gouge to the hull that exposes bare wood and goes unnoticed. A disaster waiting to happen.
This is another reason I am glad I replaced the bottom of the keel trough with rollers, otherwise I would not be able to see the bottom of the keel. And no, the rollers are not the cause of the fractures--the first one I noticed was near the aft end of the keel, beyond the keel trough that I had not yet replaced.
So, those of you who keep your boat on the water for long periods, I hope you have a way to haul it out and inspect the hull (and do so at least once a week). There have been too many horror stories on this site that were caused by water infiltration.
It is possible that trailering the boat is what causes extra stress to the keel. This is highly likely, but there is still that chance of damage while sailing that went unnoticed.
I welcome responses to this--if I am proved wrong or if you have a better solution I will be forever in your debt.
Oh, and one more thing--if your trailer has a keel trough and you can't see the bottom you need a way to lift the boat and inspect it. Here is one possible solution: https://www.jamestowndistributors.com/userportal/show_product.do?pid=98161