The City maintains a list of mobile home parks in Vista that are privately owned and that participate in the Mobile Home Accord. You can find the list online here: Vista Mobile Home Parks Listing.
Mobile home registration is handled by the State's Housing and Community Development (HCD) Department. Below is HCD's website and contact information for the San Diego office.
San Diego Office
1530 Hilton Head Road, Suite 107
El Cajon, CA 92019-4655