I also see that you have disabled the default airport vehicle library.
No, we haven't. We made a *backup* of it, and it was just patched to remove ONLY the default Pushback truck, everything else stays the same.
Could you publish info for developers, or at least provide advice about any problems that airport developers might experience when users have GSX enabled, and how to ensure our test systems can work with/without GSX (so we don't have to install and uninstall constantly or have multiple FSX installs)?
There's no need to uninstall/reinstall anything, unless you want to test using the default Pushback, but in that case you can simply copy the vehicles_airport.gsx back to .bgl and you would end up in exactly the same situation as if GSX was never installer.
About designing the AFCAD:
the most useful suggestion, assuming the file doesn't have obvious errors (like unconnected parking spots, or that can't be reached), it's usually best not doing something too complex, like too many nodes too close to each other. Reversed parking spot, were the parking orientation is the opposite of the direction of the approach link to it, are also a problem.
Service vehicles prefer to use vehicle paths, reverting to use taxiways only if there's no other path, and they also start parking spot of the type Vehicle or Fuel, thy revert starting from a regular parking spot if there's no dedicated parking. So, use vehicle paths, and put some vehicle/fuel parking in different places of the airport.
Also, try to use airline codes at the parking spot, because vehicles will read it to help defining the handling operator, and don't play with the parking radius as a trick to select the airlines that goes there (a trick which was used before FS9, that didn't had airline codes), and don't use a larger than necessary radius, to force larger airplane than what could reasonably fit in that space, FSX might be able to place them, but there might not be enough space for vehicles to maneuver, and it's likely you'll have GSX vehicles inside buildings, if the radius is set too large comparing to the actual clearance of the scenery.
