Hello BGC users!

I am designing a 2 axis gimbal that uses a geared servo to act as a 3rd axis to position the gimbal frame assembly orthogonally to the horizon. Chapter 21 of the BGC manual describes this and from what I read I thiiiiink it is possible for my setup, but I wanted to get a second opinion. Here is a image hosting link to a diagram to show how I plan to implement this: https://freeimage.host/i/JC8gKdP

In words: This is a 2 axis gimbal with encoders on each motor. Starting from the camera is the pitch motor, which then connects to the yaw motor. The base of the yaw motor will be connected to a servo assembly which rotates the entire gimbal about the pitch axis when in standard position. If the yaw axis was rotated to the right 90 degrees, then the "4th axis motor", the servo, would be aligned with the ROLL axis of the gimbal, which is a bit weird, but probably okay right?

This 4th axis servo motor not only be able to swivel the entire gimbal into an upright and downward position for dual mode operation, but will also act as stabilization in the downward mode, keeping the yaw axis vertical at as much as possible (at least about the pitch axis). The servo motor will be controlled via PWM output from the BGC and I DO wish to utilize IMU feedback to make the stabilization aspect of the 4th axis motor faster and more accurate. Preferably this IMU feedback would come directly from the BGC main IMU, but I question whether the board can be mounting only above the yaw motor in the same plane, or if it can also be mounted on the YAW arm too. The benefit of the yaw arm mounting would be that infinite yaw rotation can be possible with a gimbal mounted battery.

Do you think all this is possible? I wanted to hear others' thoughts before proceeding with my design and manufacturing a prototype.