Plus your in the California area, could also check the ads in Backpage and other type of classified publications that carry an Adult Gigs section. That's where I use to place ads when I was doing video work.
believe you me, just contact the producers. They'll be more than appreciative to entertain your inquiry about modeling. It would also help if you try to make a name for yourself, as to create a following or audience so to say, which will in turn benefit you in increasing your model reputation. Just make yourself noticed. 😉
get someone to take pictures or videos of you being tickled and hey presto, a tickle model is born, get someone to buy the pictures or videos and as if by magic, you become a professional tickle model. Isn't media fun? 😀