You really should try harder, but I'm sure they won't look at your grade 11 marks too intensely. Consider this, in grade 11 your mom/sister/aunt/cousin dies and you are unable to attend school out of grief, eventually you fail grade 12 but come back for a victory lap and leave with a 60 average. 2 years go by and you're thinking about your options, you're sick of working at K mart or wherever you work. You take courses at an accredited online school and you pull off 90's in all of your classes, putting you in the 93rd percentile. Are you telling me that they're going to look at your application and say "pff this kid is horseshit" or are they going to think "this kid's lived a little, he knows his mistakes, he's not going to mess up this chance"
All in all, pull up your socks, but don't worry about it. Life's about making mistakes, ROTP isn't looking for child prodigies, just dedicated people. They're taking a chance on you, and they're going to take a chance on the person who has the most drive to succeed.
If you don't get in you don't get in though, if it's really as hard as all of these guys are saying and they go back to your grade 8 marks, then with your 96 average from grade 12 you could just go to uoft and join a few clubs to stay active, get a co-op and pay off your school a couple years after graduating. If you really wanted to you could even apply as an officer after that....just a thought.