Yesterday I was discussing this problem with an old-timer down in the
southern tier of New York State (where bears have been a problem over the
years).
 
He knew of one beekeeper who had good success with platforms of the
following description:
 
Nine feet or more off the ground, with trap door in center of platform.
The platform itself extends out quite a bit beyond the supports.  This plus
the height make it practically impossible for bears to get to hives.
Apiarist access to the platform is from underneath, thru the trap door.
The pickup is driven right under to receive the honey supers.  He mentioned
some sort of pulley/lift arrangement possible for lowering the supers.  The
platform he described held 24 colonies; I'm not certain but think it was
enclosed/screened.  He did say the guy stored the empty supers and some
spare equipment right there on the platform.
 
I hope this is somehow useful; just thought this might lend some ideas in
the discussion of the bear problem.  Fortunately, bears are not (yet) a
problem in central NY, altho' the population of bears coming up from
southern (Pennsylvania) areas is on the increase, and they are a problem
within a 40 minute's drive from where I am.  WIth increased pressure they
could become a local nuisance in time.  Later...   JWG