+1 on the second length of stop section. I also added 2 pcs of polycarbonate, 1/8" x 4" x 72" long that run from the finish line to the far end of the stop section on either side of the track to contain a car that might derail. At the moment, I use a rolled up towel at the very end of the stop section as a crash fence but most every car stops well short of the towel. Only have the towel there because a concrete wall is at the end of the track. You can clip the polycarbonate in place using the same size binder clips that Besttrack uses to join the track sections.
For our pack's track I took a piece of memory foam in a 4" x 4" x 15" size and housed it in a wooden box that is offset down a bit so the cars that don't stop bump an inch or so up from the bottom edge. Keeps the cars from trying to burrow under the foam. One of the parents sewed up a camo fabric cover for it. That works good enough that a second one is on my todo list for my own track.