Orange County Soaring Association winches from
Hemet Airport.

You might want to check which clubs really operate out of airports in
the USA. Just because a club owns a winch, does not mean they winch
from where they are normally based. The Orange County club for
instance certainly does not winch out of the Hemet airport, they only
winch out of 29 Palms on occasion. So I throw your stats all into
doubt. I am not aware of any publicly owned airport in the USA that
allows dual winch/regular traffic operations. Of course I could be
ignorant and wrong. It would be a good exercise to factually check if
there really are any and then see how they resolved the liability/
operational issues.
Tom