I use a large crescent wrench and tighten it as much as I can by hand. After that I use a large rubber hammer and smack the crescent wrench with it to ensure it is tight. Its been three years, no issues. It sounds like your installer did not do the right thing from the beginning. The only times mine were lose were after the Jeep was aligned.
BTW, I am also interested in how someone used an impact wrench on a jam nut.
2012 JKU Sport, Rock Krawler 2.5 Flex, Smittybilt SRC Side Armor, Mesh Grille MOD, Sony Double DIN AV Receiver, Back up Camera, Kicker Speaker Upgrade, ARB Twin Compressor, Dominion Off Road High Lift Mount, Homemade Paracord Grab Handles, Nitto Trail Grapplers, Paramount Rear Bumper with Tire Carrier, KC Hilites Daylighters, under seat lock box, Metal Cloak Front Bumper, BARTACT Seat Covers, BARTACT Sun Shade, x20 Comp Winch, sPOD, ARB Air lockers, 4.10 Gears.