I thought of a neat update for the fuel trucks.
We are redoing the whole refueling function in GSX from scratch.
And yes, it will feature progressive refueling that will actual fill the plane (so you'll see it going down very slowly over its gears and yes, the fuel hose will keep stay attached to it correctly), at the realistic speed depending on actual real-world capabilities of the different vehicles pumps performances.
Different fuel trucks will have different tank capacities so, for example, you asked for 40000 gallons of fuel to be loaded on a 747, it will take 4 trips of the larger fuel truck, since its tank has 10000 gals of capacity, and will take at least 40 minutes to refuel (totally realistic), since that vehicle can pump fuel at 1000 GPM. The choice of the refueling vehicle is made depending on the airplane capacity, so the smaller planes will call for smaller trucks.
Since you might not want to wait all this time, so we also put a "Fuel Time Acceleration" slider in the settings which will go from 1x (1:1 with reality) to 10x ( 10 times faster than reality ).
And yes, this will recognize and will work in conjunction with the progressive refueling option found in popular 3rd party planes like the PMDG 777 and the Aerosoft Airbus.