I can't help with fishing but I do know you do not want to drive any RV around Toronto. Traffic is horrific at all hours. How are you approaching Toronto? Are you planning to cross into Ontario at Port Huron or Detroit or Sault Ste. Marie. If you know this information then we could suggest a c.g. outside of Toronto ( near Brampton) that would enable you to visit your friends and take day trips for fishing. There are a couple of parks west of Toronto that might work for you - also lots of golf courses in that area. Milton Heights C.G. and Bronte Prov. Park are two that come to mind.
Note that someone suggested getting a free N.P. park pass. There really are not any great N.P. in Southern Ontario for rving. Point Pelee on Lake Erie does not have camping but there are private parks nearby. Lake Erie perch is good but you would need a boat for fishing.
The only other N.P. I can think of near Toronto is Georgian Bay and it is comprised mostly of islands and is more for boaters/canoeists and backpackers.
Depending on the timing, you might like to go on a salmon charter boat into Lake Ontario.
