"...but they're in Muskoka..." Epp's is 15 minutes North of Orrillia on Hwy 11. Not Muskoka. It's worth every minute of the 2 hour or so drive. They have stuff you won't see anywhere else. There used to be an antique shop(called Ad Hominem. Dunno if they still exist.) across the parking lot that was worth a look too.
"...excepting new members..." That's the issue with TO these days. Has been for years. Tory shut down most indoor ranges soon after he was elected and now there just aren't enough memberships for the demand. Even the "hour or so drive" clubs are full. Guelph for example, hasn't taken new members or put any on their waiting list since at least 2016 and have no plans for doing so in 2019. No new members at Barrie either.
You may want to look into the CFB Borden Rod and Gun club. There are some hoops to jump through but the biggest deer track I've ever seen was on Borden.
https://www.bordenrodandgun.com/membership/
Where you are in TO matters. You really won't want to drive to Burlington or anywhere else West of TO from the East end.