Bobby - I too was actually just thinking about the tire gauge before I read your post, but not for the reason you explained as I am ignorant as to event you explained as even existing! But I was thinking perhaps that my gauge was inaccurate. It is not a .99 cent job, but it's not a super fancy thing either. It is made in the U.S., and I think it was maybe $10 or so, and looks exactly like this:
But then I remembered that I measured the air pressure of the new tires before they were mounted, and the gauge read 80 psi. That is the max pressure of the tire, and that is the pressure the tech specifically said he inflated them to. So I know at least the gauge is accurate.
As far as damaging the valve core.....I use the same gauge to check my TV tires and have probably had it for 10 years. Through its use, I've never had a tire that was constantly losing air unless it had a foreign object in the tire. Even the TM tires held air pretty consistently.....I generally never had to air to them during the course of a trip....usually only once before our once-a-month trips, and even then, maybe just 2-3 psi. And often times they wouldn't need any air at all.
Speaking of gauges, I was thinking that a dial gauge would be more accurate and/or consistent. If that's true, have you seen any that you recommend strongly?
I just ordered the TST TMPS system for the trailer. It's being delivered to the east coast so I can install it for use for our return home. I don't know if it will help, but I don't know what else to do to improve my odds at this point.
Dave