2016 Tuscany Winterize solution
I know it's been a long time and you're probably set. I just got a 2016 Tuscany and had trouble winterizing as well. I hoped it would pull antifreeze through the city inlet if I put the valve in the winterize position (since it's labeled city water / antifreeze). But after calling Thor, that is not the case. Apparently dealers have machines that will pump the antifreeze in under pressure. So I cut the line on the right that comes from the fresh water tank and used a couple of hose bib to 1/2' barb connectors and inserted a garden hose Y adapter. Now I can use those 2 valves to pull my antifreeze in via a short garden hose.