Seriously, how do i make a simple quarter mile?

I have followed the really average map modding tutorial that comes with the game and have worked out Unity enough to get the track exported but can't seem to get it running.

I have set up the track to be just a huge asphalt plane with the car set at 0,0,0 a checkpoint at 0,0,0 for the start line, and one at 0,0,402 for the finish line (roughly 1/4 mile in meters).

I have managed to upload to the workshop as private, and then download the map into the game by subscribing to it in the workshop (seems like a roundabout way to get it into the game). My track appears in the workshop maps in game, but it does not have a title or thumbnail, and it doesn't load when i click it. All my other downloaded maps from other modders still run.

Anyone tried to mod maps and can give me some pointers? I really just want a simple quartermile map that can give me run times, doesn't have to be pretty...