I think the answer to the original question is (In Europe) that a destination alternate has no defined max distance. The only requirement is to be able to carry enough fuel to divert to that alternate. This flight to diversion if over 60 mins would not be breaking the single engine rule if there were plenty of adequate airports along the diversion route and adequate does not involve weather.
I believe that some UK operators fly to the Canaries using oceanic routes, Sometimes they can be right on the 60 min limit from Santiago. Santiago weather can be below limits for landing but it is still adequate.