Aluminum corrosion - prevention ?

If aluminum isn't anodized, it will oxidize. Clear coat will look good initially but you already know what time does to that. Removing the clear coat wont be easy, whether you intend to renew the clear coat or go back to the more frequent maintenance routine.
Only positive thing I can offer, at least the wax has improved. Modern synthetic "space age polymer" sealers hold longer than the old school carnaubas.