Here are my thoughts and a bit of progress with the mushroom vents. I definitely want to be able to open and close the vents from inside the teardrop. I found some threaded knobs at my local ACE Hardware and inserted SS carriage bolts with Loctite Red for a permanent bond. I don’t know if it is visible in the photo but the middle screen section was drilled out and a brass threaded insert screwed in. I haven’t decided on how to fix the knob/bolt to the mushroom cap and will wait until I cut the vent holes through the shell. The carriage bolt will have to be shortened but not until I see how it all fits together. What I do know is I don’t want the knob sticking out just above my head so the forward vents will be in panels 2 and probably higher than the manual shows. The rear vent will be in the quarter panels pretty much as shown but also with the interior control knobs. I thinking of putting a fifth mushroom vent somewhere in the galley, sides or hatch to be determined, and maybe a butterfly vent through the bulkhead to get some air exchange in the galley on hot days. That vent would not have the internal control knob and would only be operated from the outside. 