Test run it!
It's workable -- although I would have preferred the mileage grid-radius because my target day's trip to next campground is about 180 to 250 miles and click the next line up of campgrounds like the Allstays apps in the vicinity.
The campgrounds will only show up when you key in your destinations. Then do a trial and error if the first inputted area is beyond your driving radius.
It's useful rather than accessing 3 websites and apps to do your planning.
And dang, my test ran data got lost when I signed later because it would allow you to save your trip before you sign-up.