I can't help but feel that they are all missng the point of the marine exclusion zone. it is there to stop you impaling yourself on a bloody mast !
if you extend the runway then surely you need to extend the zone or what is the fricken point of it in the first place?
Because you don't need both MEZ's at the same time! Displaced thresholds (i.e. keeping the touchdown marker in the same place) contains the same MEZ clearance from masts on arrival; conversely the calculated take-off run available, excluding the runway end safety area, and started from the displaced threshold, provides departure clearance at the other MEZ...