Since we’ve been out in sub freezing temps, I was a bit concerned about the valves being so close to this uninsulated opening. While we never had an issue, I finally took 10 minutes and cut a piece of foam padding (like you buy to make seat cushions) that fits into the opening. Probably doesn’t do anything meaningful, but sure doesn’t hurt.
Along the same line of probably meaningless RV paranoia, a couple times when we’ve been out where the temp has gotten into the teens overnight, I’ve removed the drain access panel on the bottom front of the shower basin so that at least some warm air will circulate into that space.
I think it would be great to cut slots into that panel, but I don’t have a router table to do it....