Or get a piece of paper and a Sharpie and write TBD-P.
I've personally NEVER had an attendant look at my sign and say, "park over there." In fact, the only time (in many years of doing this) that an attendant ever even acknowledged my sign, he said, "what the hell is TBD?"
Look the guy in the eye and say, "I'm here for the Two Bills Drive tailgate," and point to your left.
It's that easy.