Hello Mark,
Thank you for your message.
So long as the endpoints (Hosts) have access to the internet you can
set up the Internet-ID connection to get to the Hosts. This is the easiest way to go since you won't have to do any network configurations on the routers.
However, if you insist connecting directly (without an intermediate server) to the remote Hosts you will have to forward ports twice - once on each router. I believe this might not be an option in this case.
Hope that helps.