I use a smaller version of a household water pressure regulator. Specifically, a Zurn Wilkins NR3XL:
Below are a few photos. As you can see, I have it mounted on a small platform. I leave the two braided hoses in place, with quick connects on the end of each one. When we arrive at an RV space, I run a short hose from the water supply, quick-connect it to the input side of the regulator, slide the regulator under the coach beneath the wet bay, and quick-connect the output side of the regulator to the coach.
I have the regulator set to allow 65 to 75 PSI into the coach plumbing.