To get to the really correct drawing for that year, model, and floorplan, it has an early and late year build. That may mean there are differences in the plumbing.
To get to the correct set, do you have an RV with the 7th digit of the serial number being 1 or is it 2?
Not the VIN but serial number from Winnebago!
If not handy to dig into paperwork, etc. there is a label somewhere near the driver's left side with the needed info and details of the RV and might be easier to check?
Meanwhile we can be sure that there are at least three different tanks. One fresh, one black, and one grey. There look like there may be others on your RV, however.
Depending on build date, it looks like the tanks will not be the first freeze problem for me to worry as they tend to be big and lots of water which slows them freezing to burst.
I might worry most about the more solid plastic supply lines in the back wall that run to the shower. The plastic is harder, so more prone to splitting if frozen, much small volume, so easier to get cold as well as the tend to run up the wall in places where we get less heated air moving.
The plumbing at the wet bay that goes nearly outside with only a compartment door can also be suspect?
This is one build but may not be exact for your RV?
Looking at the furnace ducting, it seems there are no ducts into the basement and most run along the one side of the RV, which tends to leave the other side below more prone to being cold sooner?
Looking from above and from RV rear!
Click for better view!
But we need to know which you have to get more definite answers!