We can tweak a couple of knobs to effectively reduce the cell size but geo-fencing at least in my personal history with wireless has always been an nice story but too difficult to get any accuracy on without a very dense deployment of APs or some other means like network software (not reliable) or some non-802.11 locationing technology like Bluetooth.
Now, the knobs you can tweak include:
1. Reducing the mac EIRP (to tune down the antennas)
2. Setting a local probe request threshold to only allow clients with a certain signal rating to associate
3. Turning off low basic AND transmit rates
4. Configuring the SSID/VAP profile only on 1 or 2 APs in this location using the AP Specific parameters
Other than that, I would argue why this is needed with role based access and our firewall. If you have Clearpass, we can say only employees with a memberof or group of "finance" to connect to APs containing a certain AP-Name. Less SSIDs is always a good thing!