Decoys will increase the burden on the other teams. They will have to get someone to actually verify the credentials rather than some guy saying "I drove by the gateway arch and there is a big red balloon there that says DARPA on the side of it." (Yeah, my decoys would say DARPA.)
As for unsportsmanlike, you are working to advance the art of war.
As for unsportsmanlike, you are working to advance the art of war.