I’ve released an expanded Modbus/RS485 Wingboard for community design review
https://github.com/EnviroDIY/Mayfly-Modbus-Wing/tree/master/knh002-MayflyWingShield/rev8
I’d welcome design comments, on https://github.com/EnviroDIY/Mayfly-Modbus-Wing/issues/3 by Monday 2022-July-20 12noon PST. Easier to correct any possible problems early on, than find them later on the PCB. As the old clothes tailor saying goes “measure three times, cut once”. 
Discussion on desired Modbus usage or general questions could be made here. I should note that this is a private initiative, not funded by EnviroDIY, but I am using it as a part of a public discussion for an open source board design.