Well, I just got back from two weeks of boondocking in Utah (Cap Reef/Bryce/Zion). Lots of sand -- never got stuck. We rejected several sites that seemed too sandy.
The best method that I found for evaluating the sand is to dig your heels into a tire track. If you soon hit solid packed sand, that's great.
If you dig and dig and it is still soft, not great.
I will be prepping a detailed trip report and will post a link in a few weeks, after we finish rinsing the red dust off our possessions. My socks will never be the same.
