[DutchmenSport]

OK, I'm not the brightest light bulb in the box? I'm a bit confused.

Are you saying that, when hooked up to shore water with your regulator connected, your water pressure inside the camper starts out OK and then it reduces to a trickle.

When you remove the regulator and are connected to shore water, your pressure is OK?

If so, then there is something going on with the pressure regulator.

Or, when you remove the pressure regulator, does the same thing happen; water starts flowing ok initially and then it reduces? If so, then it's the campground.

Considering you have good water pressure when running from your fresh water tank and on-board water pump, I don't see there is anything going on wrong with the camper?

Have you tried disconnecting the hose from the trailer, make sure the regulator is attached to the shore water source, and simply turn on the water spigot and see if the pressure reduces as water is spewing out the end of the garden hose. That's where I'd start to eliminate the trailer having an issue.