I have to say... You're wasting a bunch of time and money by dumping antifreeze into you fresh water tank. The fittings on your water pump should only be hand tightened. Super easy to unscrew it and insert a hose.
Buy yourself one of these kits:
Camco 36543 Pump Converter Winterizing Kit https://www.amazon.com/dp/B0006JJ588..._x.Mowb9JZPD0D
Screw the hose into your pump... Stick the other end in a bottle of antifreeze, turn on your pump... Pressurizes within a few seconds.
I used a little less than 2 gallons for the whole camper.
2015 Coachmen Apex 288BHS
2014 Tundra 5.7 CrewMax