They won't care. Not knowing the rules is not accepted as an excuse.I understand and it is a fact and I am agree with you, but honestly I explained I didn't know I applied 4 times ignoring inadmissibillty, it not matter explaining that to immigration?
By all means apply for rehabilitation and then for the work permit if rehabilitation is approved.
However at the same time, I would very strongly recommend that you continue to build a future for yourself in Mexico since you may find it's very difficult to ever make it to Canada.