If I'm not mistaken, you live in California. That means that your first concern should be that it is illegal for you(or your friend) to buy, sell, or trade and native subspecies of gophersnake. My guess would be that your friend has a normal Pacific Gopher...they native to Cali and in order to legally make a trade, he would need to have a valid California Propogation Permit, unless the snake is an albino.
Aside from that...if you go out between dusk and 11:00 pm...you're likely to find your OWN female gophersnake coming out and warming up on the pavement of back roads before her evening hunt. All you need is a flashlight, pillowcase, and fishing license...