Max,
There are many sites where you can see the laws regarding towing on a per state basis -- here is one:
http://www.brakebuddy.com/Towing-Laws
Note that for any trailer or vehicle weighing over 1500 lbs in California you need brakes. Here in Oregon we also have the same 1500 lb threshold, but also must be able to stop the combination within a specified maximum distance...
I use the BrakeMaster proportional air brakes and Sterling All-Terrain tow bar from RoadMaster because my coach has air brakes and RoadMaster is a fairly local company. Any quality equivalent would work as well...
Chuck