WORST THING YOU CAN DO! With taking the restricter out you will now even use more water and run even quicker!, you need to change your shower head to one of the air type, so you will only use 1,25 gallons per hour like this one (BodySpa RV Shower Kit - White - Oxygenics 26781 - Shower - Camping World
There are different color and looks just shop for what you like.
As for running out, i do not know how many gallons your water heater is ^or 10 gallon but most newbies to camping find out quick (like you have) you ain't in Kansas anymore as to taking a nice long hot shower like home, and the reheat time dose take 15 to 20 minutes before it is hot again (washing dishes or such)
So i hope this helps and no i do not think you had the answer, but Happy Camping