If you try this yourself, I'd recommend going a bit lighter with the amount of sauce you spread on the pizza. I'd also advise cutting out each letter after you rolling the dough. I thought of the idea late in the game, so I ended up using the cookie cutters after baking the pizza. It was much messier, and resulted in a lot of "scrap pieces" of pizza (which I had no trouble eating before the party).
Have you thought of any fun ways to use baking tools for something other than their intended use? I'd love to hear about it in the comments.