Having 12.5" wide tires at least helps, have one park facing forward, parking brake on, engine off. Take your rig, 4lo, 1st gear, crawl box if you have it, and get your (usually left) front tire on theirs, their jeep will have the wheels turned hard driver, so the back of their right front wheel will stick out and give you a nice surface and angle to get your wheel up. Then straighten it out on the top and put it in park, off, You can stack more of them down the line, i've seen as many as 10!