My two cents... I don't think the problem is the numbers of rentals. I think it is why the people are renting them. When someone goes to Yellowstone or any of the great national parks, they normally go to be awed by the experience and beauty. I would bet most of the people who go this national park (let's not forget that is what it is), go to drink and party. When that is primary goal, why do you care if there are extra horse trails, new houses, the temp of the water, etc.
The fact of the matter is money talks, and we as fisherman, naturalists, and such, will never out man or out spend the river party rats. If your local and make a living off of that, why would you want it to change. Unfortunately, I think it is a lost cause. I hope not, but I think so.