My understanding is that you are totally in the right on this. If you are using a pontoon boat, and have fins on, the officer may have some grounds to think you are stretching the rules when out of sight of the road.

The best defense for something like this is to have a copy of the regs with you. You then ask the officer to "help you understand the situation", as you were unable to find any language that indicated that it was illegal to drift to a spot to fish.

By doing this, you establish that, a) you have a copy of and have read the regulations, b) that you will hold the officer to the wording of the regs, and not his interpretation of them, and c) you are open to having your understanding clarified.

This way, even if you get a ticket, you look a lot more like a responsible guy when you get to convincing a judge.

I've met most of the officers around here, and I think they are usually reasonable, when presented with a reasonable case. They just see a lot of bad actors, and I think have reason to assume the worst about a lot of society.