The gal wants a one layer sheet cake. The tiki hut is made from graham crackers, pretzels, royal icing for glue and fondant leaves for the roof. It's kinda heavy. I've never used a cake board between layers before. Any hints? I think it's gonna need some support - how do you hide the cake board?
I would cut a board to fit the bottom of your tiki hut and use your royal icing to glue it to the board.
You can easily use plastic drinking straws cut to the depth of the cake and place them strategically to even out the weight of the tiki hut. I would like the board to rest somewhat on the icing of the cake, to help keep it in place.....(if you have a long or rough transport you might want to wait to place the hut until it reaches it's destination). Then use whatever color icing you have on the cake around the tiki hut to disguise any board that might be showing. I used the grass tip to create the grass around the house.
I usually always cut my cardboard circle smaller by about an inch all the way around. You will then need to put wooden dowels in the sheet cake. I cut them so they are just even with the top of the cake. I also usually put a thin round of fondant where the cardboard will be so when they take it off to cut the cake all the icing isn't stuck to the cardboard. Hope this helps...good luck