"...Queen Elizabeth II Wildlands..." In the Provincial Park? No firearms allowed in Provincial Parks unless there's a controlled hunt.
Non-Park Crown Land is different. However, as far as the MNR is concerned, the only reason to have a firearm in the bush is for hunting. You can target shoot, but plinking is considered to be hunting. As daft as that sounds. Make sure you have a safe place with an adequate back stop amnd you should be fine. You must known exactly what and who is behind your back stop out to several miles. Don't be surprised if you get visited by a CO. Coat yourself in bug spray too.