Hi Rich, yes, after years of this or that elbow or other fitting cracking after carefully pouring antifreeze into the plumbing on Firefly, I realized the only real solution is to ensure there's no liquid in the lines or in the water tanks.  I've both blown out the lines with an air pump, and sucked them out with an adapter on our small wet-dry shop vac (see photo attached).  Just be aware that, even after draining the water heater at the lower drainage tap, there's still a lot of water in it.  It does require some experimenting to figure out how to ensure it is all clear, but once you have you can repeat the process annualy.  The only places I use antifreeze now is in the engine, the bilge and the black water tank (the latter of which can still be used in emergency situations without worrying about having some additional 'material' in there as long as it has been flushed with some eco-friendly plumbing antifreeze).

Rich-
Last year was my first attempt to minimize antifreeze use.  One by one I opened each faucet and sucked the line clear. Not sure if I did something wrong, but in the spring when I filled the tanks, it took me forever to get a water flow going back to the pump. There must have been an airlock somewhere but with all three tanks? I've noticed over the years that when any one tank starts to run dry, if I didn't immediately close that one and open up another, I would lose prime in my pump. Maybe our boat has places where each line is slightly elevated? In any event, I went back to using antifreeze this year. On a side note, I place the empty antifreeze bottles beneath the matrasses to elevate them and get some airflow to reduce mildew.