I agree that the next phase of this will be a mess, and maybe a disaster, but I don't think you can avoid it.
When a radio station signs up to carry Iowa games, they get a list of "exclusive" sponsors. If Iowa (Learfield) have a deal with Coke, you can't run an ad for Pepsi during a game. You can run anything you want in your local breaks, but not competitors in defined markets.
This is going to be the same way. If Iowa has a deal with Joe's Chevy, you can't do a NIL deal with Steve's Ford. Once they see relatively small dollars, and almost all of them will see exactly zero available dollars, they're going to want a piece of the University's pie, and they're going to argue the school is competing against them.
But I don't know what you do about that. It will be what it will be.