I heard at the Goulburn Datnats that the Lower control arm is only legal if it can't 'self adjust'.

So this solution means that one end needs to disconnected from the crossmember for adjustment to happen. It cannot be done easily on the car.

Personally, I'd cut a right and left hand thread in the lathe and make them adjustable. Seems it could be engineered but is certainly not a 'owner certified' mod.