Thanks for the update Johnex! Kind of sucks for me though because I have many of these all over the country with only access via SSH. I use them as a way to control other hardware within firewalled networks by using reverse SSH tunnels.
Ya, the proxy via port forwarding is probably the easy route but the API may allow me to script it. The routers all call home via HTTPS and can then get some commands or scripting changes back.
My recommendation is you make a custom image, that already contains all the ācallbackā home settings you might need. You can then remote update using that.