Several years ago (like 1990), Don Lowe discussed the modifications he had done on a Ultimate bipe. He used annehedral on the top wing and positive incidence on the horizontal stab to eliminate the roll coupling. all this info was in the Flying Lowe RCM column.

I built my own design ultimate using his recommendations and it flew very well with much less coupling than other bipes I had flown. I will try and find the exact numbers for you, but I am hoping this might 'jog' someone else's memory.

I have really enjoyed following this project of yours.

Good luck,
turbo