Hi texaggie1994,
The 100 psi on the 4-way Anderson Valve is the max pressure that valve is designed for. The rest of the trailer has a limit of 60 psi according to your trailer manual.
Water pressure and water flow are different. Some inexpensive pressure regulators manage pressure by restricting water flow. So you'll want to use a high-flow pressure regulator. In addition, if you're using a water filter, as the filter becomes clogged with crud from the campground water supply, both pressure and flow will be reduced.
It's also possible there could be limitations inside the trailer. One way to tell where the problem lies is to switch over to pumping water from the fresh tank. If you have good water flow while on the pump, the problem is external.
Visit the
RVWaterFilterStore.com to see some better regulators.