Direct motor control for turtle mode

We are looking into implementing a turtle mode, where the drone flips over on the ground. But we have a couple of questions how this can be best implemented.

To flip over the drone needs to use 2 motors in reverse or normal mode depending if it is upside down or not. The other two motors should not turn because they are used as a point of contact with the ground.

Looking through the code with the new control allocator, we think we should be able to use the actuator_motors topic to control the motors directly. However we seem to be competing with the control allocator for that topic. Is there a way to temporarily bypass the control allocator?

Another way would be to send roll/pitch rates but then we would need to be able to tell PX4 to disable some motors temporarily. I’m not sure if that is possible?

Last question, is this something that can be implemented in a flight task or does this need its own flight mode?