Elevator needs a strong servo..,particularly gears as it’s a single servo per side. He used Low profile standard foot print servos, I don’t think it’s worth the few grams. Since the servo arm has to be 25mm or more, you need something that is a real 35kg+
Vector is more about speed, but 20kg is probably the number as again you are using 34-38mm arms
Aileron and rudder 15kg.

I use 55kg Elevator and Flap, 28kg Aileron and Vector, I ended up with a 30kg on rudder as I had a MacGregor servo spare. Nose steering 20kg.
if you go light on torque the servo works harder…at some point it will give up and you will probably crash…