>>won't depressing lever empty antifreeze
Only if you have the water pump on or city water hooked up ... otherwise depressing the toilet lever does nothing, because the "antifreezed" line isn't under pressure.
Besides, once you run antifreeze through all your lines, some folks then blow out the antifreeze with compressed air ... because, after all, all that would be left in the lines are few pools of antifreeze ... and there'd be nothing in the lines to freeze if all the antifreeze ran out.
Michael's right. Don't turn on the pump. Don't connect to city water. Use jugged water to "flush" the toilet. If it's really cold (well below freezing) we might add a jug of antifreeze to the toilet before using.
Michael's also right ... if you are using the toilet, you are adding 98.6 F (37 C) body fluids to the mix on a regular basis. It takes a long time to bring that temp down to freeze (and by then, you're adding more.)
Hate to be so scatalogical here, but as a rule when dry camping
or winter camping, Pam doesn't flush toilet paper under #1 circumstances and instead places it discretely in a bag besides the toilet.
Under #2 circumstances, if we can't get to a pit toilet when dry camping
or winter camping, it all gets flushed ASAP, no questions asked.