Hi Owain,
isn't that exactly what the Alternate law does if left alone to fly the aeroplane?
I'm afraid not.
In ALT LAW, Pitch remains stable provided there is no ss input, but roll is direct and will constantly need an input until the aircraft is trimmed correctly. It seemed to give the PF loads of work because he hadn't practiced the technique sufficiently.
The only place to practice would be the simulator (twice a year normally - Unless he had UAS of course)