Protocol over lora (gateway-to-gateway)

Good day!
Whether prompt there is an opportunity to force two gateways to exchange data? My task is to provide data transmission over a very long distance at sea. I have two mikrotik r11e_lrora8 gateways assembled on the design of SX1308P LoRa® Picocell Gateway V1.0. I don’t need to use the LoraWan protocol, I’m interested in the possibility of implementing my own protocol on top of Lora without using picoGW_packet_forwarder. As far as I understand, LaraWan gateway sends downstream acknowledgment packets to end devices, so the other base station must hear this message at the lora PHY level.
So far, I have only managed to make a standard LoraWan packet forwarding network to a TTN server. Can someone provide a link to an example?
Can I implement my non LoraWan protocol and get the same result as here (Modbus RTU transparent over LoRa to LoRa), but only using my SX1308 controller?

Sorry for my google translate!