If you want to fish lakes that aren't huge and want to cast, then as you probably know St Clair is out.

I would, like others, recommend the Kawarthas. Tons of decent size lakes that all have lots of muskies in them. Pigeon, Upper and Lower Buckhorn, Chemong, Stoney, Sturgeon, Cameron, Balsam, and many more. They are all connected with or withoout locks but I would suggest trailering if you want to fish different ones.

I am not sure about camping, but I'm sure there would be campgrounds to be found in that area.

I would say, without a doubt, that is the best place to go for what I understand you are looking for.