Lot of information in this post, some accurate, some not.
I am a retired CA LEO who spent a lot of time working traffic enforcement and commercial enforcement. I am currently a CDL driver with all endorsements.
The answer is: you may tow 2 vehicles with your motorhome. There are certain weight restrictions which most likely will not apply to you and you may not be over 65 feet long.
CA law requires a Commercial Class A license for any person pulling any 2 trailers. If licensed out of state, you must be similarly licensed in your home state. Commercial licensing is pretty similar state to state now.
This shows the NON Commercial CA driver's license classes
http://www.dmv.ca.gov/pubs/dl648/dl648pt2.htm