I have never been real confident of any answer I've gotten on this question when researching it on the 'net over the years.
These 'facts' seem to pop up as unrefutable for Calif.:

- triples are allowed
- maximum overall combined length of 65'
- maximum length of one trailer is 40' (i've seen longer being sold though

)
- brakes and chains required on first trailer
- brakes required on second if more then 3000 pounds
this 'assumption' seem to pop up a lot:
- first trailer must be a 5'r, not a tag-a-long
i've even heard:
- 2nd (last) trailer must be a boat trailer only (boat lobbyists are too strong to mess with)
I wonder if a truck pulling a loaded toyhauler might be close to running out of GCWR before worrying too much about being able to pull another trailer behind the 5'r, unless maybe its a small 5'r.
But with all these 'facts' and assumptions listed differently on so many different websites i've seen, i have always assumed that what '56 said was the crux. I wonder if CA doesn't maybe require CDL to yank that combo down the road thereby making it outside the reach of most casual weekenders anyway. But then again, i have never heard of anyone ticketed for this and threads like this always get one or two people who say they pull doubles with some amount of regularity and have never had any problems.
We need someone in Blue around here who pulls a trailer to pony up on this question
(and by the way Tom, i almost sent you an email congratulating you on a BEAUTIFUL new (old) rig, before seeing that it was "Ron and Patty in Sacramento" not "Tom and Patty in Fresno"
I thought that was a little wierd that you posted a "nice Rig!!" response to your own thread, and then i figured out the name diff

ehhh... You have a nice rig too though Tom

)