You need to re-think your plan for your pets.
Perhaps attitudes in Europe are different but roaming cats are generally not acceptable in the US from a humane standpoint and from a social-acceptance standpoint. Roving dogs and traffic are the least of your worries; gun-toting cat-haters with bravado are a very real possibility. You must train your cats to be indoor pets, especially in a congested urban area, which SF is regardless of whatever pastoral RV site you find, and make sure they have been injected with chips to help in identifying them if they do get out.
Sorry, but in 21st century San Francisco, and most other urban and suburban areas in the US, it's cruel and negligent to let a housepet roam wild.
