Thanks Agoaliemom and Gene for the advice. I would feel better if I do use a heater on hard freeze nites for added insurance, I kind of wanted to get a small electric space heater of some kind for light winter camping anyway...any good recommendations?
Also still concerned with pulling up on one of those rings that supposedly attach to popup drain valves for HW and FW tanks. Thee things do not look very stout. Do they pull open well w/o any distress to the mechanism? I really sense that they might break if pulled on, but this is fear based on zero prior experience with such a valve.
Burl