Griso (G11) lowering

My pal is struggling with the height of his Griso. Whilst we’ll investigate other avenues for lowering the seat a bit can anyone advise on how far you can drop the yokes on the fork legs before it all gets too flighty?

Thanks.

my understanding of dropping forks is that it quickens the steering of the bike. It will also lower the front and make the prop stand “longer”

It may be that shorter springs may be answer front and rear to keep the geometry the same, ground clearance would be reduced.