Anyone with a more technical background who can maybe shed some light on why Boeing doesn't offer this option or hasn't built the system with a switch to operate the LGTU?
I expect there to be a technical reason why you shouldn't do this, maybe the LGTU is not designed to deliver enough hydraulic capacity to take all three units up, but just has enough to assist the A system which is normally still working on the elec.hyd.pump.
Ziggy