They can very well be doing damage to the leveling system, as your manual states the levelers are not designed to take the full weight of lifting the tires off the ground. The ram and/or pump seals may being weakened, the hydraulic motor may be getting some overheating. The real issue becomes that everything may seam ok when you pick up the unit when they are done and down the road the system fails due to abusive use and guess what they will say they didn't hurt a thing and OH what a coinsidence it was working just fine when you picked it up.
Dale & Terri, Lulu & Tiki (our Chihuahua's), New rescue puppy Prince - Pom/Pug mix.
2013 Tundra, Double Cab, 5.7, TRD Off-Road, 4X4, Full Tow Package
2013 Wildwood T26TBSS - Sold
2000 Gulf Stream Sun Voyager M-8357 MH, Ford Trident V10 Gasser, 35 foot.