Questions about dummy cakes

I am in preparation for a faux cake competition and have no experience with cake dummies. The design I have in mind would utilize 3 tiers with an edible tier on the bottom. I have several questions concerning this. I plan on using foam separators between the top and middle tiers. Since the separators will be cylindrical in shape and will not completely cover the bottom of the top and middle tiers, what would be the best way to cover the bottom, that is, underneath the dummy cakes? Should I cover them in fondant? Further, what would be the best way to attach the dummy cake tiers to the edible one? Keep in mind that not only will the judges be tasting the edible tier, but so will the audience. Therefore, at some point during the competition, I will need to remove the non-edible tiers in order to serve actual cake.

Any advice is helpful! Thanks so much!!

P.S. Most likely, I will partially assemble my cake once I get to the competition site.