Pretty much the way this has been done on our 177 for the past 12 years.  HOWEVER, I would be leery of not adding any antifreeze to the traps.  Realize there is room for water to freeze and expand however i  use 16 oz. of antifreeze for the 3 traps and a tad for the toilet to keep the seal moist and from drying out over the winter months.

Any RV owner can benefit greatly from understanding how to winterize an RV without using antifreeze. It will be possible for you to get your RV ready for the next severe weather and avoid any harm from happening. You can also return to your RV in good shape because winterizing it will help keep all of its features intact.

First off, turn your 2 way or 3 way valves on the rear of your HW tank to 'bypass' mode. 

2nd - open valve at top of HW tank to eliminate line pressure OR open one of your faucets to give same result.

3rd - open the HW tank drain with a 1 1/16" socket and drain - after draining put a couple wraps of teflon tape on threads and re-insert plug by hand and then snug down with ratchet.

4th - open both low point drains - located underneath - should be a decal showing location along drivers side of your r-pod.

5th - find the open 1/2" pigtail line located upstream of a plastic 2 way valve - usually located below sink, however on some models if you cannot find it turn pump on and listen where the noise of the pump is, the valve will be located nearby the pump, turn the valve all the way opposite to the direction you are currently in.

6th - close both low point drains after water stops dripping out.

7th - insert 1/2" pigtail into gallon jug rv antifreeze.

8th - turn pump on and turn each H and C on, one at a time until a good flow of pink antifreeze flows out.

9th - do the same for outside shower if you have one and toilet.

10th - I use 16 oz. antifreeze for traps and toilet (total)

Your total usage to get antifreeze through all the lines should take 2 gallons.