Free: Contests & Raffles.
Better rain gear than you can imagine. Strong tarping systems for rain and wind at camp.
Not trying to burst your bubble, but other then some cool old trees and thick brush I wouldn't consider this a backcountry hunt at all.
The number one thing to learn about that place is knowing how to set your boat with rope and anchor's so it does not get swamped or blown away by the wind and tide.
In September be prepared for mosquitoes. Lots and lots of mosquitos.