I'll come clean with what I have already done.
I used a jon boat and cut a big piece that was up out of the water, then hooked a 100 ft. cable to it and pulled it out with the tractor. That is already bucked and split.
The water is only 2-3 feet deep where the tree is resting. My thought is to wade out to where the main trunk forks apart and cut it there, leaving the main trunk still attached to the root ball and ground. Leave that limb covered section for the fish, then cut the main trunk at the root ball and haul it out.