Griffo, I was always uncomfortable with 10nm for CTAFs. Too close/late for "popups". 15nm is better. I don't understand the 30nm from Gold Coast bit; if you're not in CTA, why not keep the 15nm? Is Joe Bloggs expected to have the CG VOR on his GPS/2nd NAV? Confusing. If you're in CTA who cares where the BA is? ATC will "clear you to leave, call the CAGRO at 15nm", wouldn't they?
Put in a tower.