Stephen and Ed,
I have setup the tunneling routers on devices using OpenWRT and Ubuntu
Linux. Since OpenWRT is actually designed to be a router OS, I highly
suggest it. There are instructions for setting up a gateway using both
OSes at
http://wiki.ampr.org/
In order to route using Ubiquiti or VyOs, you must be able to compile
and run ampr-ripd in order to provide RIP44 (which is not the name as
RIPv2) on the tunnel interface.
Since VyOs is a distribution of Linux, there may be instructions on the
Internet on how to compile and/or execute ampr-ripd or rip44d.
73,
Lynwood
KB3VWG