I know this makes most cringe, but we long ago gave up on pressure regulators after have many issues with them (and we tried evey single kind you can find). Reducing the pressure makes everything involving potable water more difficult and only really saves you on the odd hose, which should be replaced every year anyway. The only issue we ever had, in years of doing this full time, is we noticed the water pump on our old class A leaking by at the wet end. The pump was a few years old and once I replaced all the seals and gaskets we never had a leak again. I know the theoretical damage that could be done given the odd high pressure at some parks, but again I've never seen this actually happen, and for most of you who only use the rig sometimes, this seems overly onerous to stifle your water pressure. That and out of hundreds of rv parks we've stayed at i've only ever seen 2 parks that had pressure over 80psi guaged, and only when we were the only folks staying at the park.
All we do now, is guage the pressure when we flush the line (you all flush the water line prior to hooking up right? especially at state park campgrounds, coliform builds quickly in un/underused water lines
, and if it's over 80psi we opt to run the pump off the tank if possible. But this has only happened twice at small parks that were plumed directly off the incoming feed header, vice a park distro head.
just my $.02