Putting up a shop in CA - fire department being a pain

Same here. And around here even if a neighbor did call they'd need to have a pretty good story for code enforcement to even bother with something like that, unless maybe you were already "on the radar" for other stuff
Yes, we were on their radar due to the same neighbor claiming that I was running a repair shop and then I was stalked by a code enforcement "officer". That apparently got him fired...