Replying to Summer Trip

So my buddies and I are planning a trip to Cali (we live in Minnesota) this summer right after college is out and before our summer jobs start...just throw some cloths in the trunk cash for gas and head out...so we are curious on what we should do...we just want to head out there for fun since none of us have been to the west coast...we plan on heading to LA then south to San Diego...haha the biggest problem though is places to stay cause hotels are expensive so could we sleep on a beach or something? haha also does anybody know if we can cross in to Tijuana with out a pass port if we are on land? we also tossed around the idea of trying to live out there and get jobs for the summer for the hell of it ha...so if anybody has any ideas or anything let me know.