Unique Model with Horizontal and Vertical motors but without pitch or roll

I have a aircraft that I am currently flying in full manual control meaning I am not using any of the flight control features PX4 can provide. I would like to add features such as altitude/position hold, heading hold, waypoint flight and precision landing. This seems like it will require a new frame to be developed. The aircraft configuration is:

2x motors - horizontal - forward/reverse
2x motors - horizontal - yaw/lateral
2x motors - vertical - altitude
Optional - 2x additional motors - horizontal - forward/reverse

The aircraft does not pitch or roll and all esc’s are reversing so the motors spin in both directions.

Any thoughts?