Max bus length

What's the realistic max bus length of master and diagnostics? I have an application that requires 2 masters at approx 100m apart from one another. Can these have master and diagnostic bus at this length?

I recall seeing in the IQAN instruction manual 40m is the recommended but maximum is 100m. Is this length take into account the 40 twists per meter, as 40 twists per meter at 100m length between modules would mean cabling of in excess of 100m actual cable length? If IQAN bus works at 250kbs, does this follow standard bus protocols and have a theoretical max of 250m @ 250kbs?

Will the soon to be added HS busses help any limitation?

I can always add an additional node to act as a midpoint transferring the data from one bus to another, effectively reducing the max length of a master bus to 50m, however it would need a diagnostics bus shared between all the master modules, which would be the maximum distance of 100m, and therefore the limitation?

Would CAN routing help me here with a central node that just runs its own independent program and routes the diagnostic bus and master bus through, and therefore has its own application file separate from the main 2 node application file?