One thing that has worked from me (I read it over at ADV rider) is to ask a local "do you know somewhere that I can setup my tent for the night?" DON'T say "Camp" as that has all kinds of negative connotations.
I did that a couple of times when I headed to Grand Canyon last Spetember and was told it was okay to setup my tent behind a gas station and another time on the edge of a farmer's field.
..Tom
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