Speaking as one who has been through a three-day, three-class tournament, you're going to need more than three or four mats, trust me.
Before Iowa went to this asinine four-day format (translate: $$$$), each of the three classes ran their first round and first round of consolations on Thursday (on eight mats), then the quarterfinals, semifinals and three rounds of consolations on Friday. Saturday afternoon was just for consolation semis and medal matches and Saturday night was the finals. It would be a great format in the new arena in Wichita for 6A, 5A and 4A.
As for moving 321A, you might as well be talking about moving the Rocky Mountains to Salina....it ain't happening.