This idea was proposed by Dave Willmott and others at Emerald Airways in the '90s.
Didn't get anywhere with the authorities - irrespective of whether the routes were over land or sea.
The proposal was for a 'spoke and hub' arrangement with single-engine turboprops feeding into larger airports where (in those days) HS748s, F27s and Electras would carry loads further.
This would have made commercial sense, it was suggested, with lower operating costs on the shorter, lighter routes.
Apparently this arrangement is common in the US (?)