You should probably have a look at the scenery, to understand why the new cargo loading system can only work with a plane with a forward cargo door.
There's a fixed plaform, and the plane must align the main cargo door to it, in order to have the loader vehicle doing only a very short travel to reach it. If you tried to align the main cargo door of a 747 or a 777 to it, the airplane nose will be too far ahead, basically touching the building.
In real life, 747s and 777s do not park there, but in the open.
So, we made a specific detection in GSX that, if the airplane main cargo door is in the back, the parking is treated as a regular cargo parking so, you can still park the airplane there and use GSX, but it will be loaded as usual, from the right side, using the baggage truck trains.
Yes, it's unfortunate there aren't too many options for 757/767/A300/MD11 in P3D4. It's a pity some plane developers doesn't seem to mind of letting their good products to die, like the PMDG MD11 or the QW757.
I even tried to reach out Qualitywings, asking if they needed any help porting the software to 64 bit (I have some experience now, having ported all our modules to V4 in time for the sim release day), but they didn't seem to be interested.
At this time, the best options in P3D V4 are both freeware:
- SkySpirit 767-300F
- Thomas Ruth A300
We can only hope Level-D will be releasing their once beautiful 767 for V4 one day...