The use of CRC1, CRC2 and MIC
I believe CRC1 is not something that can be changed in the LoRa protocol, at least in the SX1278 or RFM95W it is not something that can i can find can be changed, it just happens
In EXPLICIT mode the CRC2 can be applied - on the fly - by the transmitter so is available in the uplink and the downlink if needed. [TESTED in RFM95W]
My opinion is that if a MIC is available, forget about CRC2. If no MIC exists, apply CRC2.
Does this make sense?
If we want to be more fancy, on top of this, we can remove the CRC if previous receptions show a big link budget margin and if ACKs are missing, re-apply it.