I went from one of those 45psi brass non adjustable regulators to a watts adjustable. Big difference in water pressure. I set it to 52lbs and the water pressure coming out of the faucet is way better. Newer trailers use Pex tubing which has a higher psi threshold than older trailers. It's used in housing all across the country.
The black tank rinse hose needs to be a different one. It can be just a reg garden hose if you wish. I happen to use an older fresh water hose that we replaced with a new one.
Just an FYI when dumping the tanks I like to dump the black tank 1st, then dump the grey. While the grey is dumping I leave the black tank valve open and run the black tank rinse. That gives it a good 5 mins or longer rinse time. I purchased one of those clear hose attachments and it's amazing how much brown water keeps coming out after 10 mins of rinsing.