I had this exact problem when trqansfering my rego to the ACT in 2008 (over the pits for the initial inspection). I had a full length cargo barrier in and the rear seats removed. I had done my research having been warned that this might be raised. The compliance plate indicates the "Maximum" number of seats that can be fitted to the vehicle but most interpret this as 8 seats means 8 seats.
They sent me packing because I still had the seat belts installed therefore it was an 8 seater and they had to see the seats - fair enough, I should have removed them. So I went back to work and borrowed a pair of seats from a mates 100 series and went straight back - easier than removing the belts at teh time. Note that you have to pay an additional fee or every additional inspection. A different assessor this time tells me that my car was unroadworthy because I had seats fitted behind a cargo barrier!!
This is where I, how shall we say... lifted the tension in the building by explaining in no uncertain terms what I had been told only one hour earlier. They guy looks at me and says that "no one here would have told you that". I look over his shoulder to see the previous inspector walk into the room so I just glared and pointed saying "That bloke did!". The other inspector sensed troubled, and sheepishly backed out of the room. My anger attracted a manager who thankfully saw my predicament (and no doubt the retreating inspector) and then tells me to just take it to the car park, remove the seats and the seat belts and I'll be on my way - which is what happened. Thankfully there are other options than taking it over the pits every year. I still get questions from some mechanics doing my rego inspection even with a copy of the compliance details, but with drawers now fitted, I dont seem to have the same problem.