Thanks for the battery advice guys. I think I will go with the lawn tractor battery to power the light system, I like the idea of a small lightweight battery vs. a 75lb deep cycle! Tod, this motor doesn't have a pull start, electric only, so I kind of like the idea of having 2 batteries aboard just for insurance during the winter. I also have one of those portable power packs that I'm planning to bring along as well. Being stuck out in the marsh in sub-zero temps with a dead motor is an experience that I'm not too eager to repeat!
I absolutely agree with your approach with no pull start. That is what I'd do too. A second reserve battery that can turn the boat over is prefect. There might be a small AGM (or similar) that will fir your deep cycle needs - the ones that I did not get great service from were West Marine brand.