If you don't have a black water cleaner sprayer built in and have toilet paper and other possible solid waste that just won't breakup and go out try this.
Before you leave the camps site or from home dump a few bags of ice cubes down the toilet. Hopefully it isn't 110 degrees out but the idea is to have the trailer move down the road and the ice as long as it is a solid will hit the sides and bottom of the tank and breakup anything that may be solid or even stuck on the sensors.
I used this when my sensors were covered with paper and wahtever.
It worked for me.
Just another solution if you have cooler temps and ready to drive down the road. Oh yes you should dump the stuff after your drive down the road .