What should I have done?

I would only suggest that situations like this are why I think it wise to be just a bit slower than traffic while towing and why I dislike cruise control while towing. Neither of which would have prevented the OP's citation, but might have improved his odds. I wasn't there, so can't blame any one factor but only offer those as things to consider in trying to understand what to change to avoid another such ticket. I have been stuck unable to move over but have always been able to get one the brakes enough to avoid a ticket. Cruise control does slow my application of brakes, Best wishes to the OP in the future.