So basically, a few days before Oct 10, I found a tool (https://lapwerks.com/) that allows you to make tracks and export them to BeamNG. I decided to use this a lot and made these tracks . I will leave you to wonder what the Alonso track is.
Because they don't have custom models? You can build a gorgeous, stunning, amazing map that would weigh 0-1 megabyte if you only use assets that already exist in BeamNG.