As you said you saw in campgrounds many folks use them. I use one and I understand they only work to control side to side movement at the front of the trailer.
For the rear I use BAL telescoping stabilizer jacks which eliminate rear side to side moving.
I use a pair of adjustable chocks between the tires which eliminates fore and aft movement. Due to a med condition I have to have my trailer rock solid.
Or as some folks do....go with the JTs or that type of product if your unit has the wiggles when some one moves or walks inside the trailer.
