Not a lot of options in Muskoka to my knowledge, but there are several frequent visitors who make their way up from Barrie.
In Orillia, I enjoyed a few sessions with Easr Coast Nikki. She is a talker, with several animals and serious tats, but if you can get past those she is very good. Haven't been back since she stood me up a while back, but she seemed genuinely sorry for doing so.
Meeks in Grayvenhrst has tried to get established but I never tried her.
Beyond Orillia, Barrie has several ladies ..... Check out the Barrie ads