Tilt servo size recommendations

Im beginning a design of a Y3 style vtol plane(2 front 1 rear). The motors will be T-Motor MT4008-12 from an earlier project. Estimated weight around 4kg. I imagine the gyroscopic forces may me quite large to tilt a motor.
Can someone comment if they have had problems with servos being overpowered or gears stripping. Ill probably use standard size servo but just wondering if I can get away with the next size down (mini), if chosen carefully.
As this will be my first vtol project (many multirotor and planes so far) I am wondering about choosing props. Clearly they cant be perfect for hovering and fast forward flight. I was considering having the rear motor used for forward flight and having a larger pitch on it, but unloading it in hover by having a forward CG.
Comments welcome.

Ill also ask this question. Perhaps in the last 5 years there is more VTOL experience.
Ill add a few more questions regarding vectoring tricopter
I guess the rear motor/prop need not be the same type as the front 2 as long as it meets the lift requirements?
Can the front 2 rotate in the same direction and the rear in the opposite?
Is it recommended to offset (from vertical) the rear motor to alleviate the requited vectoring from the front 2?

So I guess the best way to check if a servo is man enough for the job is a bench test. This
HS-6975HB seems ok but Im not sure im happy with plastic gears. 8.6kgcm from this from this servo. Perhaps even a smaller one would be ok?