I have configured Cargo Main Door as the Baggage Door on the PC-12 but although the ramp vehicle arrives and the baggage (all 3 cases!) slides down the ramp and is loaded onto the baggage vehicle it never drives away. The handler just stands there.
Maybe you changed the Timings in the GSX Setting / Timings page ? Also, the loader will never drive away, just because baggage loading is done, and this is made in order to have the loader in a known position, one that is unlikely to conflict with other vehicles arriving, like catering.
It will go away when you select Departure/Pushback.
When configuring an aircraft the stock image is that of a 737 / A320 type aircraft. I accept that is a reasonable depiction as it covers so many types of aircraft. But is there any way of showing an aircraft that looks like the one I'm trying to configure with a fewer numbers of doors?
That's not normal. The airplane shape changes depending on the number of engine so, you are supposed to see the single engine image with that plane. The number of doors, of course, must be all the doors that GSX will ever support, since the whole point of configuring the airplane in GSX, is that you might eventually add doors not specified in the airplane.cfg.
Case in point, the default 737/A320/747. In the [Exits] section of the aircraft.cfg, there's just ONE cargo door and ONE service door, even if you see two or more of each type, but that's just because, since all cargo doors share the same variable, the [Exits] section will list only one of each, with the other being just a part that is animated from the same variable. But of course, in GSX, they are then separated, with vehicles going to each one, even different vehicles.
This means, if we tried to do what you are suggesting, displaying only doors that are specified by the plane, you would lose the ability to have more "logical" GSX doors than the number of "real" doors supported by the airplane.
This just with default airplanes, or 3rd party airplanes that use only default door variables. It would be impossible trying to enumerate doors on a 3rd party airplane that use custom variables, so the only way to do it, it's exactly as it is now: showing all doors that GSX can use, and let users Enable/Disable them.
I've changed the ULD Code for the Cargo Main Door to Auto and that does result in the baggage vehicle arriving and departing. But when I bring up the GSX menu it still shows Passengers deboarded. Baggage unloading in progress.
It should complete.