not sure if it helps, but I recently did a series of posts on my blog on installing Kubernetes from scratch on a set of CoreOS guests on Xen, with flannel, RBAC, TLS and so on and it does give you a cluster that you should be able to access from the outside no problem.

Link in my profile, I tried to make as low in magic as possible, I just ended up writing a couple of bash functions and a python script to make it easier to assemble the Ignition files for the deployment, but besides that it should all be step by step.