Looks good so far.
Just use some smaller Mod-Ter bricks on the routes the players are supposed to ski.
Little hills here and there will make it more fun to play.
Oh and jumps, don't forget about the jumps.
Jumps through hoops, quarter pipes, half pipes (sloped down), wall jumps, ...
You can even add rails and jumps that land on rails.
And using zone events and the onVehicleEnterZone event, you can add coins to collect.
They don't have to do much other than increase the score.