That's exactly what I did - and the only experience I had was a day on a rental bike a decade ago in Cyprus. In hindsight, I should have taken the Basic course. It worked out in the end, once it clicked but the first couple hours on the range were sketchy!
The only requirement of the IRT is you at least have your permit - which requires taking the DMV "written" test. If you already have your endorsement then even better.
Looks like they are all booked for the rest of the year in all locations though.
Oh and I'm very jealous of your location - you have Hell's Canyon in your back yard!
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