Next time you're getting ready to hit the road, make sure your tanks are dumped. Then add about 4 gallons of water and a generous amount of Dawn Dish Washing liquid and hit the road. When you get to your destination, dump the 4 gallons. The odors will be gone and your sensors will probably work again. The sloshing of the soap water in the tank will clean your tank, and the soap will keep things a bit slippery. It's a simply way to keep them clean.
My camper also has a black tank flusher and it really does not do "that" good of a job. The best solution I've found is the wand down the toilet into the black tank. That thing always cleans out the tank until clear water comes out. (I have a clear sewer hose section to see just how much junk is coming out). Add some Dawn and a few gallons of water, and drive around, and the tank never smells.