I don't think any of that apart from the last is beyond a conventional narrowboat. the reason the last is iffy, is that it is a long costal passage with little, if any, shelter along the way, so it would be very vulnerable to changes in the weather. it is also shallow in sea terms, so is likely to build up larger swells with wind.
My own personal views, others will differ.#
With the comparatively large weight of ballast, most narrowboats carry they tend, to roll less than the narrow beam suggests but are still likely to be uncomfortable. They tend to cut through waves rather than ride over them, so large waves may well swamp an open well deck. If one did roll onto its side the as long as the ballast did not move it would probably right itself like RNLI lifeboats do.
So, a thick (possibly 25mm or thicker) to avoid the need for loose ballast and any further ballast needed being steel and welded to the baseplate. Properly calculated ribs, stringers and possibly a keelson to ensure the hull can stand the extra stresses it is likely to suffer in a bad sea. No windows. but use proper marine portholes, so they are unlikely to blow in if a wave hit them. Trad stern with stern doors that can be close while boating to avoid a following wave flooding the boat. No well deck or a well deck with a removable watertight cover. Large bilge pumps for all bilges and the well deck. Folding or removable mast(s) to mount navigation lights to meet the regulations, also the VHF aerial. Valves on all the hull piercings. High (roof) level air supply vent for the engine. Exhaust with a proper high level swan neck so following waves can't flood the engine internals.
But most of all, experience and knowledge so you don't put yourself and boat into danger. The design would need experience, hence a couple of us mentioning the need for a naval architect for the design and calculations.