You can truncate the hash to cause collisions, meaning that one MAC address does not map to one location. This requires the client to be aware of multiple physically nearby MACs in order to get a location, as it then needs to estimate which "possible" locations are most likely.

This is a really interesting problem, and I've loved thinking about it recently. If you're keen on it too I'm happy to discuss further, feel free to reach out.

To put that into perspective, 48 bits is 256T, which is roughly the number of bits in a 32TB hard drive.

Absolutely right, great point. That's why I only use Windows addresses now. Can't break those with brute force!