The plan is to get a small piece of land next to a beachside and build some tiny houses for homestay business. One unit would be where we will live. Wife is a great cook so my potential customers gets a homestay package with home-made meals included.

Am looking for materials that can withstand the water vapour from the saltwater. Rust is a big problem for seaside buildings.

Agreed. It could be my second option now. Already thinking of a different plot somewhere near small streams of fresh water instead of the beaches. Like those you can find in Janda Baik. Lesser maintenance headache.