Lost Vegas to st. George

I did not pay enough attention but if you go thru the gorge there is a campground 3/4 of the way thru, if you take the Littlefield exit just before the gorge there are places where I have seen people boondocking. Between Valley of Fire and Mesquite I have seen several places where people are boondocking. And because I have not paid enough attention I am not sure which of the exits you take for any of them.
We spend three months in the area every winter.