well, ive tried too. not really into unity, was watching youtube videos, but didnt get far..... Was trying to change on the game unity files but couldnt get to edit them, idk why.

I've spent a lot of time doing unity decompilation, and level switcharoos are doable, but the thing is that everything in this game is level dependant, so the code expects there to be a playable snowmobile, terrain and other stuff, so if you could get your hands on a pro version of UnityUnpacker by DevX you theoretically could do it, but theres a lot of implementing and extracting to do before you are able to get something to run, I managed to do it with a plane and just a camera, but having the full game run in a hacked level is near impossible as far as my knowledge. It's something that I would like to try for real though.

(https://gyazo.com/6ae4beb4e34d9e67fe5f1ace72bc7d4e, just to show you I know what im talking about heres an untextured version of the suspension testing map)

And there really aren't any videos on how to do this, it's all from my own knowledge and experience.