never seen a non-padded SW20 wheel. Even the Momo wheel used on random special editions.
Sounds like you've got nothing.
Pay the fine, clear the defect, and swap it back. Its worth the risk.
interestingly, I have a mate (in VIC) who had been defected TWICE for the stock wheel in his 87 TX5. Eventually gave up and got a naff aftermarket one with a padded center.