Well I looked into what California has in the way of training, and it's odd. My Wife took her MSF course 25 years ago nearby, but now MSF seems to have no presence here at all. The state took control of motorcycle training here at some point with the California Motorcyclist Safety Program, administered by the CHP. Over 100 locations statewide.
Riding a motorcycle here requires an M1 endorsement. Completing the course waives the riding test at the DMV.
Trikes and sidecars only require the normal class C license, so I located no organized training at all for them.
The oddest thing I found was that sidecar rigs must be inspected, and registered as special construction vehicles. Why? no clue. I'm good, because I hand built my bike, and it already has a SPCN title. This may well be one of the many rules, regulations, laws that are ignored here, because the folks tasked to enforce them don't know about them either.