I'm about half a mile from the Pacific down here in SD, so not super close. The humidity is slightly higher than my last place, which was about 8 miles inland.
Had a friend who, ten or fifteen years ago, lived right on the cliff in North SD. There was a big crawl space under the house that he had to dig out and convert using plywood and insulation panels. He had some issues, but I can't remember specifics. He had a spare bedroom, but this was pre-legalization and he had a nosy landlord. The bonus about using the crawl space was that there was a secret entrance in the master closet - a hidden door maybe 3 feet tall, no handle, which he simply slid his laundry hamper in front of.