I ended up making it a 20 wagon oil train, which initially was a huge deficit (I think just shy of a million a year), but because of the longer distance a mere 6 barrels was worth something like 150k, which is much, much more than any of my shorter routes.
Add to that the goods train I was mentioning (Also an electrical – second train that comes around, which is more like the older 100kmh trains but less pulling power) and it actually turned into an almost instant success.
I think I said something along the lines of “Well that’s definitely a lesson learnt. TTD distance mechanics are entirely intact here – We’ll be doing more of these long rail-lines for sure” (of course to myself since I was talking to myself for half an hour thinking I was still streaming xD)