How many houses do you pass, James, who own a caravan and have it sitting on their drive? This may be blocking someone's view, but nothing is ever done about it!!!
A friend of ours has a caravan site - not very big, but its quite popular. She got a static caravan, intending to let it out for holidays. It was up against the side of her house, so not sticking out like a sore thumb. Someone reported it though, and it had to be moved. Yet, the field was full of tourers all summer!!!
I have a 4 berth caravan parked in front of the farmhouse - we say we are living in it, while renovating the farm (which we are). Behind the hedge I have another caravan where all the farm cats live!! I am in a green belt area too. Nothing said so far.
I cannot see why you running a business should affect whether you can have the caravan or not? You are right though, it does take forever for the council to take steps to make you move it. And its got wheels? Then it is surely classed as temporary and mobile.