Well, well, well... I have success with Dave Snow's Cotton Belt Route. Only 1.5 GB later, about 5-6 thumbnail fixes, and presto! Now the real bugger, the Joint Rail's SP GP40-2...
Jointed Rail's SP GP40-2 on NV3's TS12 after SP1, using Dave Snow's route (no problems with that route and other consists) in driving mode. I cannot couple another loco to it.