Here are some tips for the big day. I know the first site deals with decorated cakes but looks like there are good general pointers that you could glean from:
https://www.craftsy.com/cake-decorat...e-competition/
https://www.hobbyfarms.com/baking-ti...-win-prizes-2/
Also, you might visit a bakery & ask about how they transport cakes. I think you could get some good tips from them.
Good luck & most of all....have fun with it!