The problem with decreasing pressure is due to balls being inflated indoor where it's warmer.
The solution:
Take the machine that inflates the balls and all the ball completely deflated; without any residual air.
You take the machine and you lay each ball on the turf at least 1 hr before the same so they all reach the game ambient outdoor temperature.
After 1 hour or two or three, just before the game when the inflating machine and the deflated balls are all at the same outdoor temperature you then inflate all the balls to regulation pressure.
The only minor questionable variable I see is that over time the inflating machine might get warmer the longer it is running.
OPTION 2:
If the NFL allows teams to use their own balls there's another solution.
Each team deflates their balls and leave them on the field with the inflating machine so they all reach the same outdoor temperature.
Each team takes turn alternating inflating their own ball. However, the opposing team then tests the pressure on each.
If the opposing team ball is found to be off the team checking the ball can inflate it to the proper level and then the other team can measure the pressure.
Each team would keep the other honest.
Once the balls are properly inflated a neutral party maintains possession of the balls until needed so no one can stick a inflating needle to release air (although that could be done ON the field DURING play by any player hiding an inflating needle on their person).
The Colts are the only team which has been caught with needles on the field. Not just in the 2014 AFCCG. There was, by the way, no punishment for it.
Really, this is all just silliness. Yes, you can go and make every football the same exact pressure on the field - but just the side judge holding one between plays will cause variation (approximately .1 PSI per 2 F) beyond what the NFL is fussing about.
The ball being wet is many times the variation. Or muddy.
And again...6 PSI over the course of the season, and no one apparently noticed in decades - including the ex-QBs that were outraged, and who’d played with footballs with lower pressure.
This was just about doing a gotcha against the Patriots (the NFL itself violated multiple procedures in multiple ways), that backfired because the League was completely unaware of 8th grade science and this thing called “outdoors”. Instead of admitting it, the NFL offices doubled down on stupid.
The QBs are much more concerned about the feel of the footballs, and no QB is going to have a training staff introduce variations in pressure to footballs after they’ve gotten the balls the way they’d like.
Actually, if you watch the infamous Bill Nye video, note a couple of things: he never measured the actual pressure after took the balls out of the refrigerator, and...he proclaimed that he couldn’t tell the difference in the now underinflated balls - which was exactly the opposite of the point he was trying to make.
http://www.avclub.com/article/bill-nye-also-investigates-science-deflate-gate-214608