If you're winterizing between outings and your outings are fairly close together I'd just blow the lines out. Here's what I do.
01) Open all low point drains.
02) Drain water heater.
03) Run water pump till completely empty of water.
04) Put drain plug back in heater finger tight.
05) Hook up air compressor to city water inlet and make sure regulator is set to 45psi.
06) Close low point drains.
07) Remove outside shower hose and head.
08) Open all faucets one at a time, first the hot then cold side and let blow till no more water comes out.
09) Open all faucets, low point drains and remove water heater drain plug and continue to blow out until no water is present.
10) Pour one cup of antifreeze down each drain. (sink, lavatory, shower, toilet.)
11) Set thermostat to 40º (lowest setting) and turn to heat.
Number 11 is optional. We do it so we don't have to remove canned items. We usually go every couple of weeks so it doesn't sit very long. It doesn't get very cold here so the furnace runs very little.
Salem 29RKSS Pushing a 2500 Mega-Cab CTD!
Gotta go campin!