As you know some slabs of ribs are inherently longer than others. Using the PBC can cause an issue because there is the risk of the slab touching the hot charcoal when the meat is hung from the rebar.
One trick that was beneficial to me was double hooking longer slabs and hanging the meat from the second hook. (The hook that is furthest from the rebar) This positions the meat further away from the coals.
During the cook, the meat should shrink. At this point, (using both hands)I use one hook remover to gently lift the slab off the rebar, while using another hook remover to re-hang the meat on the rebar by the 1st hook. If you don't have two hook removers, and nice set of metal tongs can be used to hold the meat while you re-hang the meat.
I hope this helps! Don't burn those ends!