It’s not so simple that one should keep two days. There is a serious question of bittul Torah as well.
Each person should speak with their Rebbe, and follow their advice.
In terms of American investors in Israel – please come live in those vacation apartments? Imagine all the impact to your neshama and the economy is you lived here!
Every Jew has a right to live here. But if you choose to ignore your right to live here, it’s not pashut that you have the same right to dictate Israeli policy. It’s like the famous line – American Zionists are happy to fight down to the last Israeli. You have a right to an opinion, but not a right to vote. But move here, and you can shape our future!