I have done multi-master RS485 many years back. I found the AN01230 interesting in how they achieve the multimaster operation.

What I did involved a little an extra 485 chip, but, essentially utilised the same principles.

I had a main RS485 transmitter and a separate RS485 listener chip on the same board. Whatever goes out the transmit line is visible back again on the input line via the listener chip. So, any data corruption due to a collision can be detected and the transmit process can be re-started. The rest of the arbitration process is essentially the same except I use discrete IDs for each RS485 station like in any such multi-device setup and the system worked very well.

You can stop transmitting the moment you see a single byte error in your packet - when sent character is not same as received character.