2 Lucky, you can just name all your toys inside one book. The title is .............CASH.
I do hope your spare tire isn't named, Slash.
When you get caught up, could you tell me more about your E-bikes please. We looked at them at the Outdoor Expo in GJ last weekend. I'm more interested in the value to your usage than the tech aspect. Do you take them on all your trips? Do you use them around town? Do you ride the trails? Would you use the rack on , Flash? How do you lock them up and do you worry about the battery being stolen? How often do you use the assist? I really like the idea and I understand they are pricey. I just want to be sure that we would use them enough to justify the cost. Let's just say my knees haven't been 18 for many years so they are pushing me to do some investigating.
The inlet fitting includes an integral check-valve which is supposed to keep water from running back out the inlet. Since this connects to the waste tanks, the check-valve is a safety measure to prevent contamination of your filler hose. Perhaps your check valve is stuck open now. This could explain why you didn't notice this last year. If so, you should consider replacing the inlet fitting. I had to do this last year. Replacement part cost about $30 and was easy to install.
But of course none of this answers your question. If the check valve is doing its job, it seems to me that the water remaining in the flush lines could freeze and bust the pipes. But I've never heard of this happening. I wonder why.