I don't blow out the lines, just drain them as previously posted. Here in winter it gets a very few degrees below freezing for only a couple days in a row. Once in a while we can get a "hard freeze" but it doesn't last long.
If we were not in the banana belt, I would do a proper winterize, but the OP seems to be in a similar climate to ours.
Not sure what people do here when full-timing. It is not like Saskabush or somewhere like that. We get "snowbirds" from Alberta full-timing on the Island instead of going to Mexico these days, since it got so complicated to go South after 9/11 (or 11/9 depending on your convention)