Here's the go ( may not apply for "roof rubbing") : take out travel insurance, which for me when I did a motorbike ride from Cape York to Cairns (9 days) and then flew to the Gold Coast for another 14 days to holiday with the wife and kids, cost me under $70. This will allow you to say to the car hire company with a big smile on your face that no I DO NOT want your excess insurance.
You can say that because most? travel insurance policies cover you for damage to hire vehicles used on gazzetted roads when being driven by the insured person.
My examples are 1: My mate on the Cape York motorbike trip hit a tree on The Frechmans Track and did about $400 damage to the bike ( beat himself up as well ) but because the trip was an organized tour with registered bikes that were effectively on a hire contract on a recognized road - for those that know the Frenchmans Track you can argue that it aint a road but even though you have to carry the bikes through river crossings and it is just a set of 4wd ruts it is a road - he was able to claim the amount back on the travel insurance.
example 2: On the same trip my 7 year old daughter decided to put her feet on the side window of a hired Tarago while driving up the Bruce hwy resulting in glass spraying all over the hwy . New hire car required and bill received later for $300 which went straight to the travel insurer which they "happily" paid.
Booking hire cars with Gold credit cards is also cost effective because they have insurance built in that is really quite good and can save you heaps if your trip goes haywire or you damage a hire car.


Hope this helps if your planning a trip in a hire car in the future......