Huh... that's my old stomping ground. Where's your start point?/ End point?

Most of the wineries are ok w/ sweatty cyclists. They see em all the time.
Oh, and I'd talk to Mike at Geneva Bicycle Center. He, more than anyone, probably knows the best way to go about this kind of ride. My dad, when he was still alive, would do a loop around the lake once or twice a year (or more). And Mike was his go-to for bike stuff.

If you do drop by there tell him that Sam says hi.