I use the Watts N55BG Regulator from RV Water Filter Store. I also use a Surge Protector. ALWAYS. If you're worried about the cost of buying either one you're missing the reason for using them.
The cost of repair out weights the cost of prevention.
If you have a water leak in your trailer the damage that can be done is in the thousands of dollars. I don't remember who it was but they left the trailer around 8am in the morning and got back around 5pm. Water from the bedroom sink hose that was blown off due to high pressure covered the entire trailer. It was totaled. The floor and walls were soaked to the point that the wood would rot.
Many on this forum was at the Nashville Rally at the KOA that had been flooded out by the storm. How many trailers had to go to the shop due to being blown out by excessive voltage.
I came back to my trailer at a state park that had 110# pressure and one of the filter containers I use on the outside of my trailer was busted. On the outside of the container it said.... Maximum pressure 100#. The whole area was covered with water. Luckily they were not in the trailer. Many people will turn off the water at the post when they leave. I keep my regulator set at 55# and so far have not had a problem.
If you don't want to buy a regulator that is your choice. I don't hook up without either one.
FWIW
BC