I'm way out of my league here, being only a nocive recreational pilot, but wouldn't pouring the well developed UK-CAA and Norwegian regulations and requirements regarding safe Notth Sea operations into mandatory EASA ruling solve part of the issue?
That way compliance with the high off shore standards would be mandated for all EU Operators, moving around AOCs won't change anything and the free markte advocates won't be able to complain. Win-win, sortof.