Thanks for your reply Jerry. So you don’t think the end was sealed while on the back seat of Frazier's car? Oswald simply relied on some fold over to stop bits escaping?
I think if the paper was heavy enough, it probably would have retained its crinkled shape on the end. That end could have been pushed into the seam or gap of the back seat (where the seat-back meets the seat) to ensure it stayed close and prevent the bag itself from sliding around. The small loose bits inside could have been in a smaller bag inside the larger bag or in his pockets. Or he could have loosely re-attached all the screws and kept the disassembly to a few loose parts. That would also keep track of where the original screws went.
If a two-foot-long bag, I would expect most people would just take it into the front seat for the trip.