When remixing, you must come with either a Character + Kart, Course to race in, or both. Fill in everything needed and you will be qualified. Be creative when making your kart! Put yourself inside the kart design. P.S. If you're making a course be sure to include music to race w/ in the background, and it can include hazards to be precise. Press the "!" button to show all the hazards the remixer has decided to add.
You might have to scale down the truck a little.