At the recommendation of Tone, I went and got some Trailhead auto deflators. Awesome!!!! I got the 15-40 psi set. I started out at 34lbs, and had them deflated to 18lbs in less than 10 minutes. I could have cut 3 or 4 minutes off of that, but I have TPMS sensors on the valve stems that have to be removed with a spanner wrench. That takes a few extra minutes, damn anti-theft...
I will repost times with fillup once I get my CO2 tank filled. It took about 10 minutes more to refill them off of my big compressor in the garage.
These are not a necessity, but I cannot imagine trying to airdown at the trailhead one tire at a time manually. These things were really accurate, all within .5 lbs each, and that was on first time, with just 1 turn adjustment.
I highly recommend, Ebay, about 60bucks shipped.