When you are dumping today....dump and rinse 3 or 4 times. If you have a rinse inlet, cool..if you don't you may have to drag a hose inside and poke it down the toilet. Don't be worried overly about the sensor. They are all crap, anyway. You just to make sure that you have gotten any build-up out. Sure..some Simple Green now, before you go to the dump place. Let is slosh around some.
After dumping till you figure you have it...put in a bunch of water...5 or 6 gallons. Throw in your Simple Green and let it be.
The vacuum created by open windows will draw smell into the cab. You won't get any smell till after a week. So...every 5 days, dump.
Gary Haupt