I honestly couldn't tell you. But my guess is they won't help much. The primary use of rudder
foils so far is to provide automatic pitch
responce to fast boats. As the bows drive down the AOA of the rudder
foils pulls the sterns down, and when the bows lift
the AOA changes to lift
the stern as well.
Technically you could set them to always have a positive AOA and try to lift the stern, but it would create a lot of drag. How much? I have no idea. I know that the crossover speed on maxi
tri's to switch to lifting foils is around 20kn, below that the foils add more drag than they prevent. After that they are magical.
Even foiling cats like the A's don't set the rudder foils to directly create lift. As the dagger boards
lift the bow the rudders just gain the AOA necessary to lift as well.