What is “all tread”?  Do you mean a piece of threaded rod threaded into the cap on one end and a knob on the other end? If so you will need to jettison your baffle, which is held in place by the nut.  The only problem I see with that is if you are in your camper andmitmis raining cats andndogs andmyou wish to open your vent, there will be no baffle to keep rain water fro coming through your vent.  The baffle is essential mission critical to prevent leaks. The second problem is finding angle that will stick to ABS plastic.  If there is an answer to these problems, your idea is attractive.