Those Air-Through Caps are called Gator, Crocodile, V2B, and I think Schrader or Dill also offers them. They are:
Simply the Best
The Hot Setup
The Bees' Knees
Mama's Pajamas
They're "airless" because they don't press the actual valve stem till you push the air gauge or air chuck onto them. Till then, they provide a secondary seal against Air Loss and Dirt Entry.
I can see where if you ran in mud, you'd either have to wipe/brush the tips clean before use - or just use quality metal caps with gaskets instead. That's what Borg used to come with, chrome gasketed caps.
My tire checking time is well under 5 minutes unless the vinyl covers are still on or I go under the bed to check the spare.
Remember, with Tire-Man or Borg valves, tire checking is simply checking. Unless you picked up a puncture, there is no air loss for months at a time. Too bad in a way because checking is so easy it's just about fun.
