You are NOT going to like it with a 12x4P prop.

Stick with the 11x7.

I didn't bother with the single elevator servo as I did not forsee a big advantage to all of the effort.

I use the rudder all the time on landings, so I'd say that you would be ill-advised to eliminate the rudders altogether.
I also prefer the dual rudder servo arrangement, as I had a problem one day with a servo that caused the surface to turn out on one side. I was able to turn the stick the other way to even things out while the plane was in flight, so I brought the plane in uneventfully.