If you're going to take this approach, a bigger question is why bother running the SSH jumpbox 24/7 in the first place? Shut down the SSH jumpbox when you don't

If you're going to take this approach, a bigger question is why bother running the SSH jumpbox 24/7 in the first place? Shut down the SSH jumpbox when you don't need it (thus achieving SSH isolation) and start it up with your public IP in user-data to enable access to you and only you when you do need it.