I have been thinking about this for quite some time.  I wanted to be certain before I cut more holes in the shell.  What are peoples thoughts on this- adding a gasket to the inside of the mushroom vent dome so it seals tightly against the shell mounting bracket for travel and for draft protection in colder weather?  I also like the idea of a nut/handle/threaded rod so that the vent can be opened and closed while inside the TD.  I haven’t figured out how to bodge that together yet though…