I assume the issue you had was not the vtol take off itself but the following conventional flight, it did work very unstably in regular flight, i think the issue was slightly on the center of lift and most importantly, the size of the control surfaces + the very small vertical stab, it gave the plane too much nose authority, i also angled the wings down, it may have helped slightly, and sized up the vertical stabilizers as it would slide pretty violently.

If you have issues with the vtol takeoff itself, try only tapping the controls, only hold when the movement is too great for a tap to do the trick

I do not think i can make it work with any smaller a vertical stab, due to the configuration of the plane, maybe making them down pointing will be the way to do it