I've just been living in a seaside town, and even there everything became corroded in a few weeks. The humid salty air is enough to rust my steel frame bike on sight. If you keep on top of it you should be Ok ish. Keep the bike rinsed off with fresh water. Do keep it covered on rainy/stormy days, grease and re grease with marine grade grease all threads and mating metal. Then see if you can find a garage to store it away from the sea.
Good luck.