I don't see a wing area listed, but based on the wingspan, if the wing shape is fairly close to scale the wing should yield close to 1260 sq."
Wing loading at 20# would be 36.6 oz/sq' , Cubic loading at 20# would be about 13. With those flaps, landings should be uneventful.
Interested to see how much ballast your model with the 35ra requires, if it is at least 20oz, the 55ra would not increase AUW of the plane.