My personal preference would be to call the MATZ as early as possible, once a service is established inform the MATZ controller of my intention to call the aerodrome to do the ATZ crossing and then call the MATZ back once through the ATZ. A bit more complicated than some suggestions above but I think it would give the MATZ controller a lot less stress than having an aircraft arriving in the MATZ and then asking for a crossing/service. Of course the MATZ controller may well be in communication with the aerodrome and be able to clear you through themselves (don't know about that, just being hopeful
) Asking locals and phoning ahead would play a major part in determining what action to take in individual scenarios.
Would anybody consider using multiple radios for this, i.e. telling the MATZ that you are calling the aerodrome on com2? Is that legal?
D