Some people like a scope on a shotgun. I have never understood why. You need no magnification at turkey ranges. It just makes it harder to find your target in the scope at real close range. But if you decide to go that way, lowest power you can get. Mount it as far forward as you can and still crane your neck forward enough to see a clear view. This protects you from getting your face cut. And do not use a scope with a spring loaded recoil absorbing stock.
If you want to use a reflex sight but are dead set against batteries, Trijicon makes sights that use both fiber optic and Tritium night site technology that require no batteries. But they ain't cheap.