Doubtful the vendors will set aside a tank just for RVers who desire ULSD. IF they buy diesel and it is ULSD, it will be mixed into the same old tank they use for diesel.
What vendor with multiple stations would spend money to appease a couple hundred people? Business wise, it just does not make any sense to think anything much is going to change until Federal Government regulations demand such a change.
And, an article today in Mexico papers said that not to expect the price to change from what it currently is selling at. THAT is not what this is about.