The main lake side of Frye island has lots of drop offs and deep water flats. Good area for jig, troll and if your after smallies there are plenty around. Boat traffic is rough on weekends and the channel up to long lake is very crowded at times.
Trolling flat lines on the main lake can be productive but costly because ski and pleasure boats will pass close behind you and break you off. During the week its much better.
The wind will be rough at times since there is only one island (Frye) to break it. I have delt with waves 4 feet and higher. If you have fished the broads on Winnipesaukee on a windy day, Sebago is worse
In decent weather, Sebago is a great fishery and very scenic.
Enjoy your trip
John