The new one supposedly has a water heater bypass, but its not real accessible.
I would get bypass available if possible or you're going to thru this every year.
Mine is in behind a closet, Totally stupid the way it was put in IMO. I came up with taping a pair of opened vice grip pliers on end of broom stick to get the teeth over by pass valve and turn.
I know every RV is different, they all seem to have their problems. When I drain my water system I can get just about everything and don't worry about freezing. ALL except my water valve on the toilet. For some reason air pressure doesn't get out all water and I have to use anti freeze just for that one valve. The little anti freeze I use for that one valve takes a long time to get rid of. Flushing out 6 gallon would take a long time IMO.