California has their famous ‘Agricultural Checkpoints’ where they now check for everything illegal there, guns, ammo, Phonics Math books, meat, Trump caps, oh yea, and fruits and vegetables coming in. Soon they’ll add generators.
But one workaround - if you have a medium to large RV, even if not registered in CA, it will normally have a generator for campground use. So perhaps you visit there and ‘forget’ to bring the generator home with you. That will work, as they do not inspect outgoing traffic.
In the end, entropy always wins