Welcome to the crowd. I'm not very familiar with fishing, as I'm not a fisherman myself, but I can give you some very general hints. My brothers-in-law are avid fishermen, so this comes up quite often in family gatherings. My own experience of fishing is over 30 years ago when I went with them to a little fish camp 8 hrs north of Montreal, 5 hrs of very rough logging roads included. On my first day I got 13 Northern Pike, the biggest over 40", on the next day I got nothing at all. Talk about beginner's luck. As a general rule, if a lake is easy to get to, it has seen many a rod. If you are interested in fishing with outfitters, there are some outfits on Lake Ontario with a good reputation for finding really big Muskie. The lakes near the 1000 islands are ok, but not as spectacular as anything in the near north or the far north, so it comes down to how far you want to drive. The farthest you can drive on this side with an RV is about 2/3 up James Bay on the Quebec side, over 1000 miles north of Montreal. The road is fairly good asphalt all the way up to the town of Raddison (400 inhabitants) and the Cree Indian town of Chisasibi (4000 inhabitants). Between Matagami and Raddison you have about 640 km without services exept at km 384 with a gas station, cafeteria and dormitories. There are rustic campsites about every 100 km, always at a lake. They only offer a space for you rig, mostly any size, (I even saw two Prévost up there), a picnic table, dry privvies and a common water pump. There is also an emergency radio-telephone every 100 km or so. The best fishing of course is with fly-in camps.
You could try the following sites for more info:http://www.ontarioparks.com/english/index.html
Check out especially Algonquin Park here.http://www.campgrounds.org/index.cfm?member=opca
Check out areas 5a & b and area 6.http://www.municipalite.baie-james.qc.ca/h...e_accueil00.htm
This is to dream about the reall big ones, but you have to travel far.