If you ever get to Oz then you will need to be able to use propane
. Butane might be available, but it would not be common.
I have seen stainless steel tanks for sale
at an extortionate price
I doubt if any of the refillers would be happy with aluminium or fibreglass tanks as they are (to the best of my knowledge) not used here. They may refuse to touch them.
My installer accepted a steel
tank on the basis that it would be exchanged each time it was refilled but that is reaching an envelope edge.
I brought a second galvanised tank for not too much money
and it looks much sturdier than the steel one. I believe these are fully acceptable for marine
use. This would be the way to go if you can get one. Make sure it has been recently tested.