There is another option. And I am kind of surprised it doesn't exist, or maybe it does and I am not aware of it.

Someone who has a BGP announced allocation, like HamWan (for the US) could create their own (open source) portal for remote (non RF-LAN) users. They could also support things like OpenVPN in addition to IPIP, etc. I envisioned a series of regional portals, where non-RF users would hook up with the one closest to them. If you are in Europe for instance, I am pretty sure there is someone over there with a BGP announcement, and there could he a Europe portal for IPIP (and possibly other types of connections) to register with rather than back all the way to UCSD.