Heart shaped board doesn't fit heart shaped cake??!!! Help!

Hi Everyone,

I baked a 12" fruit cake 3 months ago for a wedding which is next Saturday. I baked it in a invicta bakeware heart shaped tin. I have just put a layer of marzipan on it and have placed it on the cake drum/board only to discover that the shape of the cake and the cake board are quite different. I have a 7mm gap between the edge of the marzipan’d cake and the board at the point/ front of the heart which then tapers off. If it was a sponge cake then I would normally just fill the gap with buttercream until the cake and board then became the same shape and size but as this is a fruit cake I’m in a quandary as to what I should do.

Any advice you can give would be very welcome x