I like the dual aileron servo idea...more likely to need that servo size in future, this size plane will be a once and done I think....so..
Battery Turnigy 2s 2400 or four AA batteries 6 volts
No Bec
My Flysky ia6b receiver
two Hitech HS-645MG High Torque, Metal Gear Premium Sport Servo (or similar) per wing dual aileron/elevator ... total of four servos on rear wing
Any other thoughts?
I have lots of thoughts!
For a start I would definitely use a 5A BEC so that I can use standard low voltage equipment. In addition 5 A should be enough for a large number of servos or a number of large servos. AA batteries would not last if there is a requirement for a lot of control inputs. You need to remember that the terminal voltage folds quickly under load unless using NIMH and even then they can go flat and have their voltage collapse without warning. The weight of an external BEC would be insignificant considering the load.
I would ensure that all wings are mounted on the top of the fuselage as this allows the fuselage to take the forces of the landing and not the wings. In addition I would add dihedral to at least the rear wing or possibly even both wings.
Top mounted wings will also allow for adjusting the wing incidences more easily. Initially I would have the bird with the rear wing having a small amount of incidence, (around 1 to 2 degrees and the front wing slightly more. By increasing the incidences the wings will lift better regardless of the chosen airfoil and with the front wing having slightly more incidence when a stall occurs the nose will drop thereby avoiding a total loss of control and possibly a spin.
Control surfaces could be full span elevons though in my opinion outboard ailerons and inboard elevators would allow for easier setup, the use of cheaper servos and better handling.
DO not forget the bungee launch hook or the towline attachment point.
Just my thoughts!
Have fun!