In Emeryville on SF Bay there is an expensive Asian Restaurant near the
ramp. Their customers have no problem parking in the trailer area, but
if a
trailer person parks outside the trailer area, they get a ticket. Unless
they park on the street about 1/2 mile + away.
Maybe you should leave a nasty note on every car parked there without
a trailer.
Maybe poke their tire valve stems in the paper so they pay attention.

Nah, use chopsticks.