2nd Semi-Isolated Network

I know there are various threads about similar situations, but I am not fully understanding them and how this is setup.

I have my home network, on one of those new ORBI mesh systems, I am ultimately aiming to send some internet access about 600 feet away to a second property of mine.

But before I even get to the outdoor bridge system, I am trying to have the 2nd network set up at my house so that I am only blasting an isolated network, not my main home network.

So set up is like this...

2nd Semi-Isolated Network