How would I go about getting a corporate sponsorship for a cross-country road trip?

A couple friends and I are planning on going from NJ to CA and back the summer of next year. I was thinking buying a used camper van would be the best bet, since we could cook our own food and sleep for free. I was wondering what route I could take to get this trip sponsored, playing off the high visibility aspects and ability to promote the company at places we go. Any suggestions welcome.