As an installer, is there a way that I can test a beacon from my location, using a client's g.sheet, when I am outside their geofence?
Yes, using simulation.
SIMULATION

Under normal conditions the dataset associated with any given client is provided with a geofence. This virtual fence is described as a circle, of fixed size, draw around the client location (or centroid). The size of the circle varies to meet the design requirements and can be 1km or greater. This area defines the locations where the BPS data will be available for use. Areas outside of the geofence are not exposed to the data and, as such, not subject to the downloading of BPS updates for areas outside of their travels.
Testing Software

There are occasions, however, when a certified Beacon Positioning System (BPS) consultant may want to test the client g.sheet while outside the geofence.
BlindSquare Simulation

Here we employ a powerful feature of BlindSquare known as Simulation. From any location a party using BlindSquare can "project themselves" to any destination on earth. This is typically used to pre-plan a trip to a location previously unknown or simple to "adventure around" exploring distant locations from a comfy chair in a coffee shop, or a couch at home. However, we can also use it to simulate presence within a geofence.
To test a local beacon in a client-dataset (g.sheet) just add a beacon (or beacons) in our physical possession to the client's g.sheet. After activating and publishing, the beacon-in-hand will respond in the same way as if it was at the client location Now, load BlindSquare and SIMULATE the client location. Your virtual presence, just as if you had entered the geofence by literal travel, will trigger the downloading of BPS data. The physical beacon will now respond, just as if you were in the client facility. Once tested, if desired, the test beacon can be shipped to the client location with installation instructions - or removed/deactivated from the client g.sheet when testing is completed. Ending Simulation, regardless of the g.sheet settings, will return BlindSquare to local geography.
Try it! ...the power of BlindSquare now with extra-purpose.