I don't know if this has been suggested before, but I believe I may have a way to make transport rides function as actual transportation devices.
Forgive me if this is difficult to articulate, but basically what if you made it so the transport rides (monorail, train, chairlift) had their entrances, exits, and station platforms have an extra bit of tile data that causes them to double in function as a footpath. Maybe you'd have to somehow do some trickery to link the stations, or add such footpath data to track pieces as well, but would it not cause the transport rides to be treated as part of the footpath algorithm?