Not the advice you want but go to a real independent plumbing store and have them build the system you want from name brand components.

Thanks, will do.

1) Check your local building code first before spending any money. Depending on how that is plumbed, it might not pass code due to water saving standards.

2) Also, unless you have a tankless water heater, it might be prudent to determine the maximum flow rate of that shower system (gallons per minute) and compare that to the capacity in gallons of your existing water heater to figure out how many minutes you can shower before you start running out of how water.