John,
Failure to do so is grounds for losing one's allocation.
I wholeheartedly agree with you; but in practice, that has not been the case (see the archive).
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I'd love to help begin testing this concept. My 44GW should currently forward traffic to other IPENCAP destinations. You'd simply have to use my GW's public IP as your tunnel's default route. If this works, then we simply have to work on connectivity and peering of the other GWs providing the service.
Please be mindful that return traffic will take a path via the route in the other endpoint's route table; meaning, that the destination 44GW must be using the current Encap file or RIP44.
-KB3VWG 44.60.44.0/24