Those sticking points may prove difficult. All I can suggest is finding a local insurance broker in Cairns, preferably with an introduction to them from someone that you know, and ask them to see what they can find for you.
There will be coverage available from someone, but of course you then need to check them out re: payment of claims and other reputation aspects. It might depend on what you want the most: coverage for an asset that is valuable to you, or third party liability coverage that a marina will insist you have before allowing you to stay even for 1 day. If the key aspect is the latter, then a broker should be able to find something for you.
If you are able to provide a Report from a qualified marine surveyor to the broker that would help, particularly if you also supplied a plan and timetable for rectification of anything noted in the Report as needing attention.