What area is the property in and are the locals likely to be disgruntled about firearm use? If your firearms are licenced for rec hunt & shoot and you have permission from the landholder then sure....there is no such malarkey in WA about property zoning like I believe there is in some states.
However; what may trip you up is that Section 23 (9a) of the
Firearms Act says "A person who from any place, discharges any firearm, or any shot, bullet, or other missile from a firearm, to the danger of,
or in a manner to cause fear to, the public or any person, commits an offence."
All someone has to allege is that your clay busting causes them fear and you will potentially fall foul of that. The long story short....is speak to the neighbours to make sure they won't mind the noise and use some common sense.
EDIT: That offence also relates partially to ensuring that your projectile doesn't leave the fenceline....property size is one thing but what's the lay of the land as well? Are you bound by trees etc or is it open country? Are there houses within close proximity? Major roadways? etc etc