Unless I can buy the board at my baker's wholesale place then no I would not place my cake directly on it. I know a lot of people use foamcore board for their cakes, the only way I would feel comfortable doing that is if the cake was on a "cake circle" then that was placed on the foamcore. That way the cake does not come in direct contact with the board or the contact paper you may cover the board with.
When you're in business selling cakes and baked goods as many of us are then it's our responsibility to use products that are food safe. I never understood why some people would take the risk of using things that are NOT food safe. Is it really worth the pennies that you may save?
When a product leaves my kitchen, I have piece of mind knowing that everything that went into it and that the cake is placed on and in, is food safe. I don't want the HD breathing down my back, but if they do they won't find any reason to shut me down.
Sorry for the lecture, but it's a pet peeve of mine when I have read some of the threads in the past about bakers using "unconventional" things on cakes. Our clients are putting their trust in our hands, so it is a big deal.