Aeroplanes are not the issue. Trislanders run a bus service from Southampton to Alderney in similarly exciting weather conditions.
The Islanders are available with turbines and there's lots of other possibilites as outlined above.
The issue is the gross over engineering of the airfield operations and infrastructure and a stubborn determination to do nothing about it.
The airfield could never be IFR without a(nother) realignment of the runway and then only landing from the South with a go around over the water.