Winterizing questions in June... Not gonna make any friends here
... Who am I kidding everyone is friendly here!
You will get differing opinions on this... But I personally am a fan of using both. Clear the lines as much as possible with air pressure and then add antifreeze. RV antifreeze is not meant to be diluted, it loses it's effectiveness the more water you add to the mix.
Your winter trip options will depend a lot on your travel plans. The easiest solution is to leave the RV completely winterized until you get to a Southern destination. If you have to stop part way down and need access to your water then you will need to explore options to protect your plumbing system, and those will depend on things such as wether you are at full hook up sites vs boondocking. I assume your rig has tank heaters, they will help some. You can also fend of some of the ill effects of the cold by knowing what cupboards your lines run through, open those cupboard doors to allow the heat from your coach to travel along the lines.