Chose frame for specific Y(T) quadcopter

I’m building a specific quadcopter that looks like T and includes 2X2 contra-roter motors at the end of head T and a 1X2 contra-roter motors at the end of tail T
the 80% of trust come from 2X2 contra-roter motors and the rest come from 1X2 contra-roter motors
my question is what would be the best frame for such a quadcopter and how to implement the geometry of the quadcopter(distance of motors from CG) in my PID control

any tip really appreciated