I had a 2011 Blue Ridge with the rear half bath. If you haven't already, I would HIGHLY recommend you install a Tornado tank flush system on the rear black tank. The front comes factory with a tank flush system, but if the Salem is like the Blue Ridge, the back doesn't.
We dumped every trip, every campground. The only times we didn't dump the rear black tank was when the wife and I went alone without the kids and didn't use it.
If the black tank isn't full, run clean water in it until it is at least 2/3 full before dumping, then use the tornado flusher as you dump. If the level indicator doesn't read 'empty' when finished dumping, close the black valve and refill with clean water until the indicator is lit solid on 2/3 and "bumping" the full light, then dump again. When finished, I always added back 2 to 3 gallons of water and a bottle of sewer treatment. I've never had problems with level indicators, sewer valves, or odors. I'm a bit OCD about my tank maintenance, but where holding tanks are concerned, a little time investment in proper care will save you a bunch of headaches down the road.
