I have a 2022 13' with no bathroom.  The plumbing consists of the sink, an outdoor shower, and a tankless water heater.  The past two years I did a traditional winterizing according to the owner's manual.  I'm wondering if I can mostly rely on just blowing the water out of the hoses this year.  I still have a few weeks before I have to worry about freezing temperatures, so can change my mind.  But, what I've done so far is (1) drained fresh water and gray water tanks, (2) used a compressor at 30 psi on the city water inlet, opening one of the four valves at a time (hot and cold each for the sink and outdoor shower) to blow out any water.  The two cold water valves just spit out very little water, but the hot water values generated considerable flow before emptying. (3) I disconnected both sides of the water pump to drain any water in the hose between the fresh water tank and the pump, between the pump and the connection to the main cold water line, and any water that dripped out of the pump itself.  I plan on putting a little bit of anti-freeze down the sink drain because there is probably water in the u-bend under the sink. 

So, my question is, am I good for the winter, or do I absolutely need to put anti-freeze into the plumbing system according to the owner's manual?  It isn't that big a deal to do this, but it would be a little more convenient to just have to disinfect in the system in the spring and not worry about flushing out the antifreeze.