I am making a 14" & 8" tiered castle cake using the Wilton's Castle Kit. My problem...a 13"x9" base is too small as well as a 16" circle base. The turrets won't fit on either base. It's too late to go to the store right now. Perhaps I'll have to use a uhaul box. Does Wilton make larger bases than those I've listed?
Thank you!

A U-Haul box is fine. Just cover it with something attractive. If you haven't cut your own cake boards out of cardboard, there is a trick to it. Cut two or three pieces the same size so it will support the weight of the cake. The trick part is to put the corrugated lines on the cardboard like this:

Bottom cardboard, make the corrugations go this direction: _ (horizontal)
Middle cardboard, make the corrugations go this direction: l (vertical)
Top cardboard, make the corrugations go this direction: _ (horizontal)

This will give your cake board the needed strength so it will not bend.

You can use a rolled piece of duck tape between each cardboard layer, then tape the layers together on the rim when you are finished. Just cover the cardboard with aluminum foil and tape it to the bottom. Put your cleanest piece face up directly under the aluminum foil so if it tears when the cake is cut, the cardboard underneath will look ok.

p.s. The tape on the rim and bottom should be clear scotch tape or clear packing tape, NOT duck tape.