A big enclosure is.. well.. big. The problem with bike locks, is that they
have to be light enough to be moved with the bike. I point out, that an
impractically large lock can be used, were it to stay by the space.
So, people can cycle to the space and have a lock waiting there for them to
tie up their bike.

A simple example is buying a beast of a chain (such as those used for
anchors), and a heavy duty lock (cheaper than a bike one, because it's not
expensive light material) Weld/tie the chain to an immoveable object and
keep the keys in the space. Bonus points for RFID managed key release
system.

Were a thief to see chains as thick as their fingers wrapped around a bike,
I think they'd look for easier targets.