Jay Honeck writes:

No, they specifically okay that practice in the lease. But bikes,
cars, motorcycles, and anything "non-aeronautical" is banned
(according to their reading of the rules) at all other times -- even
if there is ample room around the aircraft.

In my opinion, this is a gross mis-reading of the FARs, which were put
in place to make sure that airport hangars were not used as cheap
storage units for boats and other non-aircraft.

If they own the land, they can impose lots of additional restrictions well
above and beyond anything in the FARs.