We have stayed at Glen Rouge Campground a number of times while in the Toronto area. It is in the east end, nearby the zoo. The GO station is not far away. This is a train to downtown and beyond.
Glen Rouge has some pull through sites, some are 50 amp. It is a very attractive place as well. You may want to reserve ahead, though. Get on the website and find out when reservations open and reserve right away. We do this every time we want our favourite site.
https://trca.ca/parks/glen-rouge-campground/