Lake Champlain 8 mile swim

Hello swimmers, I am new to this website and I'm thrilled with all of the information and expertise you all have to share. I am entering the 8 mile swim across Lake Champlain. It begins on the New York side of the lake and ends in Vermont. I have started swimming 2700 - 3600 yards in the pool 2-3x a week. I am hoping to get in the lake soon....I just want it to get above 50 degrees! I am a rookie and would appreciate any advice on workouts, nutrition, and any other tips. I have competed in 1.2 and 5 mile open water swims. This seems so much bigger to me. I am both excited and nervous. One thing that surprised me was that they allow fins. Has anyone out there raced with fins? Any pros/cons to share? I look forward to some replies. Thanks!