First time post☺:

I am not a professional baker but my friend has asked me to make her display wedding cake and order sheet cakes for 200 guests. I am happy to do it and she knows I'm not experienced and it's at her own risk lol

The bpards should be covered w/something that is greas-proof like special foils or fondant before the cake is placed on it.  I've even heard of people using that new plastic wrap that sticks to it's self. 

That's press & seal plastic wrap mentioned up there ^^^.   Also, if the cake is already on the board you can cut strips of fondant and lay them on the board to cover stains.

another idea is to buy small paper lace doilies and cut them in half and slide the cut edge under the iced cake before you border it --

and when you score a cake -- you don't cut all the way through -- and make sure your board doesn't wiggle at all -- needs to be doubled or tripled even so it doesn't bend and you can avoid the gaps --  tape or hot glue them together -- or wrap with food safe paper -- your lattice is very pretty there --

best to you