@pz1, I didn't at any point think you were out to defeat TTN -- my apologies if that was the impression I gave.
I'm not clear on what you envision, e.g. if you want your nodes to connect to the gateway using HTTP, or if you meant the nodes using LoRaWAN as per usual, but the gateway connecting to some other service and passing the node packets over HTTP. If you could elaborate that would be great.
Perhaps you mean some kind of split at the gateway -- i.e. public and private routing of packages, for instance don't pass private packets onto TTN/the Internet but forward them to a local service, though still forward packets from other nodes (e.g. neighboring farmers) to the TTN as usual?
I'm not sure how that fits in with the current architecture and design, but if it does not, it might not be too bad to simply pull the messages back down from the handler to your own local server. Sure it causes you a roundtrip instead of intercepting the packets at the gateway, but it might be cleaner and offer you other benefits. I'm not qualified to say anything definite on this, but one thing I would worry about would be rogue or misconfigured gateways, e.g. one gateway turning into a black hole for packets that should go onto the TTN.