I would suggest you get a quote for the insurance premium for the aircraft and workers comp for yourself, you may find after paying these, and your living expenses it will be costing you money to work.
Don't even think of not having insurance, if you ding a prop and end up having the engine stripped the bill will make your eyes water. Have a chat to a nice friendly engineer and get an idea of some of the bills they send out, especially if a recovery is involved, think two engineers plus pilot in a twin flying from Cairns (you pay travelling time as well), workshop labour and parts.
Also if you are injured on the job, consider the cost of a medivac alone, before you even get to hospital. Last time I was in Australia, Medicare didn't pay for work place injuries.
IF you are desperate enough to sign this, make sure you get professional advice first as to what's legal and enforcable. Possibly you could sign in the knowledge that it would be laughed out of court (pay your own workers comp though). Join a union before you start, I'd have the TWU on my side just in case.