Teeing off water heater supply to new barn service

[regenman]

I am running a new water service line to an exterior barn and want to tee just prior the home water heater inlet. The WH supply is 3/4" copper. The run to the barn is 185 ft. I am looking at 3/4" pvc to the barn unless 1" is going to be better flow/pressure. The barn will include (2) frost free hydrants and a livestock shower stall. (1) of the frost free hydrants will supply a garden as needed. Logistically this is preferred over tapping the main supply. I am getting ready to test flow and pressure at the hot water feed. Any advice or suggestions is greatly appreciated.