I suspect you have a restricted faucet not a pressure problem. Remember that pressure and volume are two different things. You can have high volume with low pressure and visa versa. An "expensive" regulator should not affect volume. Pipe obstructions are the cause of low flow, if the source has good volume.
Check the screens on the regulator, inlets, and faucets.
If your flow is restricted with both the fresh tank pump and street spigot then it is likely inside faucets. If it is only restricted with the street supply and regulator then it is likely the screens in the hose or regulator to the RV.