I recall one time where a guy had done that on his '80s pickup, was really stoked with the softer ride and great flex, at least for a while. He was with our group on his first trail run and within about 2 miles on the trail, those springs wound up when he started to wheel hop on a steep climb, ended up in a nice S-shape, and his axle was resting on the bump stops. Luckily he had some extra long shackles with extra holes and was able to drop the shackle bolt down to the end and limp home. He ended up getting the springs re-arched and put the overload leaves back in. Those overloads do serve multiple functions, as an overload and that tall clamp in back is part of their anti-wrap feature.