How about the obvious solution of not having ANY data transfer out? Encrypt and sign the data via NaCL or similar, send via UDP duplicated 5-10 times, no respo

How about the obvious solution of not having ANY data transfer out? Encrypt and sign the data via NaCL or similar, send via UDP duplicated 5-10 times, no response at all from the server (it's analytics, it doesn't matter if very few events are lost and you can even estimate the rate). As for the REST API, deprecate it and if still needed place it on whatever 3 VPS services have the lowest costs, and use low TTL DNS round-robin with something removing from DNS hosts that are down.