Just start by putting in 4 gallons and then datalog. If you're having a lot of corrections then add some more ethanol and adjust the fuel scalar. Repeat this process until your logs look good.
Also, i would suggest adding LPFP req and act to your logging list. Once you get close to 40% ethanol some cars LPFPs can't keep up.
"I'm not surprised you get along well with all the other neighbours. If you put fifty children with Down's syndrome in a room there is going to be a lot of hugging." David Thorne