Not surprisingly, the Parade Warehouses are still being used for their intended purpose, storing all those parade floats. I honestly don't think HHN would be using soundstage 25 if they were able to use the parade warehouses, as they would make an easy #11 and #12.
But since they are using 25 instead, one has to look elsewhere for a possible 12th house. I don't doubt it's going to be a cluster in the front with the soundstages, but at the same time it's a cluster of tents on the opposite side with F&F in the middle. Put a couple big IP's in soundstages, and a couple in the tents (whichever size may work for them).
Something which could possibly help is the return of the lagoon show, as there's something for that side of the lagoon.