Have you asked if wheel chocks would be allowed? I always carry a set in the truck. I have never seen a braking mechanism for a hot dog cart, at least not what it sounds like they are asking for. Sometimes you need to draw these idiot bureaucrats a picture. The last time I ran into an issue like this, I pulled my trailer up to the township offices and gave them a tour. It worked, and $250 later I had a permit good for a year.