My friend Trasee made a home for her beach property and is selling it on the Marketplace:
https://marketplace.secondlife.com/p/TD-Homes-Monterey-Beach-House/6623296
It should fit very well on the land you describe. It's very open, breezy, and works very well on a beach. Plus, it's well under the 200 prim land impact you're looking for. Follow the link on the MP entry to see it inworld.