I would stay away from mexico if you like that truck and don't want the police to steal it from you. Costa Rica is where its at.

Are you talking Baja or mainland? With only 8 days, Baja is where you want to go.
Besides Mexico can be sketch....that's another thread though...

Rosarita beach is cool...do you surf? I'm guessing not otherwise you probably would have already been to Baja ;). Go to the book store and get a travel book on Baja. The tip is
the best or so I've heard, but honestly, you need a book, a map and your wits! Seriously, Baja is more tame than mainland, but it's still Mexico and you can be robbed blind! They can smell a tourist with no travel experience a mile away. Read up and bring someone along if you can. Sorry don't mean to freak you out! Here is a travel tip, hide your money in random places... so if you do have to "donate" some of your funds they will think you have given them everything you have. Travel smart.

Good luck...