Colin, I'll bet the current Californians can point out the bargain agencies. I will say each year the contracts' fine print increasingly leans more in favor of the agencies than the consumer. My latest rental club annual agreement states I'm even responsible for damage related to "acts of God." Only point is to be sure you are satisfied with the coverage you get.
But about insurance per se - the categories we use here don't synch with the insurance categories used in Australia. I'm open to anyone else expanding on this ... but our basic minimum break out is expressed as three numbers, such as 20/40/10; or 50/100/25 which express how many thousands of dollars the insurance will pay for a covered accident in the respective categories Max Medical per person/Max Medical per accident/Max property damage (i.e., vehicle). Each state has its own miniumum. California probably has the highest minimum so if you are covered in California the limites should be sufficient for Nevada, too. My guess is some of the local people can tell you what the minimums are and give you advice on other coverages. Some states let you get, or mandate, "no-fault" which is a certain amount that is paid regardless of who is to blame. Otherwise the insurance company of the party that "caused" the accident is ultimately responsible. A good company will pay the expenses up front then collect from the other party's if necessary and appropriate. Getting a police report and witness statements can go a long way to simplifying the claim process, if that should become necessary.
Incidentally, when I hired a car in Britain a few years ago, they arranged for max coverage under Britain's rules (actually, I was told there was only one level in Britain). On top of that I used an umbrella policy here, that stated it would cover any costs over the British coverage up to the level of my umbrella coverage. I confirmed this with my insurance agent before I left.