seems PMDG MD11F fuel loading through the FMS is much faster than GSX.
That's not a problem, GSX doesn't care how fast a 3rd party airplane will refuel, as long as it will do it continuously.
Also, it continues to load fuel while waiting for the 2nd truck.
That's exactly the same as with any other 3rd party airplane with a progressive refuel system, like the 777 or the Aerosoft Airbus.
They don't communicate with GSX, since there will be a need for some kind of protocol which would require some cooperation between us and the plane developers, since they MUST update the airplane code to support "pausing" of the refueling system while the GSX truck is going away and a new one hasn't arrived yet.
unless there would be a different way of configuring the aircraft so that it behaves as though it did not have automatic progressive fueling build in(?)
Couldn't you simply load the fuel instantly ? At least, while we try to figure out if and why there are problems with the progressive refueling of the MD11 and not, with the 777 or the Aerosoft Airbus.