You certainly don't have to rent anything, even for the 30 days, but it is probably the easiest way.
The following official Nevada DMV page lists the requirements for proving your identity.
http://dmvnv.com/dlresidency.htm
You have to provide two of the documents on that page to prove your residency. The easiest two for most people is a bank statement and a rent receipt.
However, in addition to a bank statement one of the other documents they will accept is any non medical bill. Therefore, if you know someone or get to know someone (or just pay someone a small amount to receive a couple of pieces of mail for you) in Nevada you could receive a bill and a bank statement and that would be enough for proof of residency.
Almost anyone you do business with will send a bill on demand, including your cell phone provider.
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Last time I mentioned this on this forum someone gave me crap about "committing fraud" and cheating the government, but isn't that what we are all doing when we give an official residence address that we have no intention of staying at?
The fact is, our lifestyle is frowned upon by the government because we don't have a set address. Even if you rent an RV space for 30 days the assumption on behalf of the state is that you will continue living there, even if they don't ever check that. Since our way of life is not officially accepted by the state of Nevada we have to jump through whatever hoops necessary to get a driver's license and establish residency. It's just a matter of finding which hoops are easiest for you to jump though.