Parking rules?

(California)

I'm a store owner in a small downtown. Occasionally I receive shipments from a 25' truck. These loads take 5 to 15 min to unload. There is no designated loading curb, and what town ever has enough open curbside parking to accommodate a 25' truck?

Usually the driver double parks and unloads as quickly as possible. The police complain to me every time. I've asked the city where then are drivers supposed to park. They have told me they don't know. What is a driver supposed to do?

Is there a law that allows a truck to legally double park? Or am I just out of luck? Any advice from experienced drivers on what I can say to the city or solutions? God bless all you truck drivers!

I know your job is not easy.