FYI folks...I used to run proxies on my subnet in the past. The only issue was, that since subnet is not not BGP, it was intended for your use only (i.e. not using AMPRGW for Internet, but still able to use EchoLink).
I agree it is probably not a good idea to run proxies or relays on a network only connected via tunnels. That would pose a load on AMPRGW. In that case it would be better to run them there. But other volunteers in that area have now stepped up.
I used the Java JAR that was available form EchoLink (I understand you have a C program). I also used the Linux version, but the EchoLink Validators stated that should not be used without permission (and only for conference servers).
The Java version uses lots of resources... The C program was written to mimic the Java version closely but in a more efficient way, both because it is in C and because a single instance can run multiple proxies. Later I received the C source of the relay program from EchoLink and merged its functions with the proxy program so these can both run on the same system. This is in full agreement with EchoLink, and they very much welcome the hosting of proxies and relays around the world to help users that are on limited internet connections or are not proficient in configuring port forwarding on their routers.
Fortunately in our circles we have people who understand the internet and its protocols. (vs the applications that are now called "the internet")
Rob