take the back seat out, limit its load to 544kg, no reason not to go RAAus. the J230 can carry 4 ppl. and has a designed MTOW well above the RAus limit. just remove rear seats. dont load above the legal MTOW and off you go.
there are quite a few aircraft that are well over the RAAus MTOW limit but still carry numbered rego. a few Piper Pacers come to mind.