Selling a Canadian titled car in Mexico might be complicated, but I agree with Seafox. Unless it is a classic. Sell it. If it is a Classic, leaving it anywhere in Mexico is not a good idea.
One possible solution: Sell the car in Canada
. Rent a car in the US one way to El Paso or other border town. Drive it home, load up, take your stuff to the boat, and drive it back to the US side of the border. Then take public transportation (that will be the exciting part) back to San Carlos
. Yes I know the rental company is touchy about taking cars into Mexico. I might forget to tell them. Oops. Sorry.
Two adages I like: It's easier to ask for forgiveness than permission. Never ask a question if you don't like the probable answer.