[Daryles]

We have a 2019 3130re. Your floor plan (bathroom) is similar to ours.
With our floor plan, we were told to get the forward tanks to drain and a good flush on the black tank, raise the front and tilt a little to the left.
Before winterizing, I lower the front and fill the black tank. Then raise the front as high as it will go and tilt it a little to the left so the sewer pipe drains too. Then pull the dump valve. Run the flush system and let it drain really good. To drain my galley tank I lower the front all the way.
Do the galley tank first or you will have to raise it again to empty the sewer pipe.