F9 Rideshare Static loads requirements

[sXplorer]

I'm trying to understand the spaceX rideshare static load requirements in the Rideshare Users Guide (version 10-2022, attached).
For the static loads you have to test for both axial and lateral loads (section 3.3.2.2), but on a shaker you can only test one axis at a time. 
They give an example:

In the case of a 260 kg Payload with an axial center-of-gravity 300 mm along XPL on a 24” diameter interface, testing would need to achieve an equivalent line load of 32.1 N/mm, as defined by the concurrent 11-g lateral and 2.5-g axial design requirement. In turn, this could be achieved by applying 12.3-g in the lateral direction via a single-axis test.

The orientations can be found on page 5 and the load requirements (11g lateral and 2.5g axial) can be found on page 9.
I can't understand how they calculated the equivalent line load of 32.1 N/mm.  Or how applying 12.3g in the lateral direction achieves that equivalent line load.
I've been playing around for two days trying to draw out the diagrams, using vector math and torques, and googling "equivalent line load" to try and learn and figure out the calculations, but I haven't got anywhere.
If anyone can explain how they are calculating this, or better yet, point me toward some resources I could study, I would really appreciate it.