Maybe you should get an adjustable pressure regulator. A while back, we lost our water supply at the stick house. The plumber that came out said "It's a pressure regulator problem". I told him that the builder had said we didn't need a regulator because the city supply was only around 45 psi.
He went to a fire hydrant at the corner (3 lots away) and measured 96 psi! After 20 minutes digging, he unearthed the remains of a regulator designed for crawl-space installation that had been buried in the dirt. It was jsut a pile of rust. Fortunately, it had failed closed, rather than causing a big geyser in the front yard.
He installed an all brass and stainless steel adjustable regulator (Watts, I think). We can now adjust things to get the pressure and flow rates we want. We've set it at about 55 psi, as the showers in both bathrooms are fixed flow rate.
A regulator like that, but not in the fancy materials for buried in the ground installation, would at least let you adjust the inlet pressure to get the flow you want at the various outlets. With an inlet pressure gauge, you could tell whether the CG water pressure is good.
By the time we were through, I was out about $450 for the plumber and the regulator and then another $400 for a replacement impeller for the hot water recirculation pump. Isn't home ownership a blast? I'd much rather have been able to call the landlord and say "Come and fix it."
The possibility of plumbing blockages in your rig is still high, as you say the pressure has deteriorated over time. Maybe an investigation to see what pressure/flow relationships exist at major outlets like the shower would help to track down a blocked or collapsed pipe.
At least plumbing is a bit easier to investigate than electricity and you'll only get wet, rather than electrocuted.
Frank and Eileen
No longer RVers or FR owners