I wouldn't even try a private campground. Out West we have all kinds of BLM land where you could do whatever you wanted.
Where you are, I would look for a public campground with pull-thru sites that are parallel to the road so the side of your truck away from the road isn't visible. Then quietly do both brakes on the hidden side. Once you have it apart, they can't really ask you to leave. And if you're hidden, no one will even know you're doing it. Then find a similar site on the other side of the road so you can do the other side.
