Just stick some Bells on as wheels or something. I don't think a Gyroid shaped Kart with wheels would look that odd, not with how I'm picturing it anyway...Especially compared to some of the designs they already have
I don't think the logic behind the Glider matters too much either. The F-Zero cars can 'sort of' glide (they do hover after all) yet Captain Falcon's car is there, which is a good argument for wheels as well I guess.
As for the actual glider, the Animal Crossing leaf logo seems like an obvious choice. Maybe a balloon, though that doesn't seem as great.