I had crappy shower flow. Bought a decent high flow regulator (6 or 7 gpm) that I could adjust pressure if need be. Replaced the shower head with a Oxygenic (which is rated at 2.5 gpm and removed the flow restrictive orifice (drilled it out) in the shower line. Not quite as good as home, but a world better.
Depending what you want to do with the trailer there are many flow restrictors build into the system to control water usage. Took forever to fill a stock pot in the kitchen so that restrictor went in the trash as well.
Good luck and enjoy.