[Rob. Smith]

Ha Ha Ha ! Here in the police state NSW. My engineer told me to register my cobra without a windscreen to beat spectral gloss, demister, and wiper issues ( to beat emissions changes deadline) The dude at the blue slip inspection said "You need a roll-bar and a windscreen and wipers and a demister" I told him to ring my engineer but he insisted on ringing the RTA.
The RTA had recently relegated their inspectors to advisory positions and given their jobs to 'garages'. When this pea-nut rang the RTA "advisor" that bloke abused him so loudly I could hear it on the phone against the p-nuts ear ! I enjoyed that moment.
Basically you don't need a roll-bar in an open/convertible car. Take Mazdas and MGs for example. Good luck with the rego.