Mac, i use the rud to ele mix on a switch and also mixed in some rud to ail to help with wing vert on the same switch. if it dives to the belly then add some up ele when rud is applied and same with the ele and it will help but not cure, depends on how fast the plane is going so it will vary so i mixed in just enough on both to handle the middle curve and stick the rest, hope this helps.

also i have a hover switch and mixed in a little aileron to rud so the torque roll lightens up a bit, but you may like rolling