I've been in some CG's with weak water pressure so I suggest you start with checking the pressure before it goes into the rig. Need to know what you are starting with. When I'm in one of these CG's I fill my fresh water tank and run my pump to get a better shower. Then turn the pump off and use the weak city water pressure to flush toilets etc..
Other than checking all the screens, aerators, "y" valve at water supply with narrow passages, etc... you might try removing the flow restrictors. I drilled out the shower flow restrictor and changed the shower head to get a better shower.
There is flow rate and then there is pressure. Most pressure regulators etc restrict flow rate which is needed for a proper shower.
2012 Sundance 3100RB w/Reese Goose Box
2004 Ford F350 6.0 L PSD, CC, DRW, long bed, B&W drop ball hitch, Firestone Ride-rite air bags.