Cool. I am about to do exactly same thing but possibly DIY simply mount. Just few thoughts:
This is much better than other top mounted Gear360 shown on YT. Since we are taking photos/videos of the ground and little of the sky, Mavic will not block the downward view. If you can do hand launch/catch, extended legs will be unnecessary.
Loved your "belly rub"
Also I did noticed that you had gimbal lock improperly attached (approx 4:25 when cover is taken off). Did you noticed that? You know that gimbal has special guides and slot to be aligned with camera lense while it is locked? Yours appeared to be just hanging in front of the mount.
See how I do this...
I did notice that... This was my second take, and I was getting sweaty. Thanks for your tips. I have a better attachment now from Shapeways. I am planning to put one on the bottom and top. Stay tuned!