[Glenn the fifth]

Hello all, another successful camping season is now over and it is time to "put her to bed" for the approaching winter. First off- I live up near Seattle and it seldom gets down to even the low 20s in the winter here. My trailer is under cover, but not an enclosed cover in the front or back (open carport of sorts). I always take the anode out of the hot water heater to drain the tank and inspect the rod. I drain the fresh water tank by opening the valve in back just below it and I then always blow out the water lines with 30 lb air opening each faucet and the shower until all water is out. I have never put RV antifreeze in the trailer either by pumping it into the water lines or by pouring it into the "pee traps" of the drains. I leave the fantasic fan vent open about an inch and leave a small ceramic heater in the trailer set at 45 degrees. I open the cabinet doors to allow air flow under the kitchen sink and leave the bathroom door open to allow air flow in there too. My question is- do I really need to blow out the water lines? I have always wondered if I just open what I believe are the "low point drains" under the service center (two water lines that stick out the bottom of the trailer with a blue and red cap on them (I think those are the colors), would that drain most, if not all water out of the lines? Once again, looking for opinions. Thanks in advance for any advice or suggestions. -Glenn