I've been trying to do this for a couple of weeks. I have no idea what I'm doing and it's been hard to find any help via google. But I finished it last friday. Without multiple external IP addresses. Funny to see this as the top story when I woke up today. But yes, as caleblloyd says, it's 2017. Use SNI. It's not hard, I'd never even heard of nginx or letsencrypt before I started my project.