terrible location for water pump on 2014 keystone retreat

[buddy1]

We recently purchased a 2014 keystone retreat 39fk park model, and i finally found where the water pump is located,would you believe behind the fireplace!! i am prepping to winterize the rig and thought instead of removing the faux stone and fireplace to access the pump, can i just pour 5 gallons of antifreeze in the empty fresh water tank and pump it through the system with the hot water tank bypass selected? i have never heard of such a silly location for a water pump right behind a 120 v electric heater