Is Naturist Hiking Legal?
In general yes, hiking naked is legal in Arizona as long as you are aware of the specific scenarios when it is not. Those scenarios come down to State Law and specific use restrictions on Public Land.
State Law is defined by https://www.azleg.gov/ars/13/01402.htm and essentially says it is illegal if "the defendant is reckless about whether the other person, as a reasonable person, would be offended or alarmed by the act. " I've been hiking here 30 years and have generally followed the guidelines that by sticking to remote and less popular parts of Arizona a reasonable person may be surprised, but not "offended." And generally when I see someone coming on the trail ahead I can cover up with something and simply be as polite as possible. I've never encountered any more than either amusement or disinterest.
Land use restrictions apply in the National Forests via a "Forest Order" that is issued periodically to address illegal uses of the National Forests. The restrictions vary by the Forest. For example the Tonto prohibits nudity (https://www.fs.usda.gov/sites/nfs/files/r03/tonto/publication/alerts/03-12-00-22-04%20Occupancy%20and%20Use%20Restrictions.pdf) as of Feb 2022 but did not before that. The Coconino only prohibits nudity around the day use areas of Wet Beaver Creek (https://www.fs.usda.gov/r03/coconino/recreation/wet-beaver-creek). The other National Forests and BLM land in AZ do not specifically address nudity.
So basically I have chosen to avoid populated areas while nude hiking which is not difficult since I would avoid populated areas if I were hiking clothed. And considering the chronic lack of man-power within our Public Lands I'm operating under the assumption that I would be very low on the enforcement priority list.