Thanks for the reply. I know about getting the IDP through AAA for $15 and two photos - had I known about it while I was in the states, I certainly would have done it. But it's now too late. I'll be there in less than two weeks so I can't wait for them to send it to me.

Good news is that Budget finally replied, 3 days after my email inquiry, that my US driver's license alone was sufficient for them and also for the police. I'll just go with that.