This is an awesome MOD, used your m motor and servo placement in my own version, but ended up only using 2 L motors for power and changing it to wheels. Moves pretty well though.
I have to say this is amazing, You have done an incredible job would love to get my hands on something like this. Really wish Lego made more Train models.
The original ski piece was replaced with the newer one without the hinge part, Original listed as 1993-2014. Could be that this was one of the last sets packed and that's why there is a difference. Just checked on Bricklink and the newer one without hinge is listed as an Alternate piece in 10218