I bought that stupid wand too. ditch it.
Fill up you tank with water and some cleaning agent and dump and repeat the process a couple of times. That's really all you need to do.
Note: you don't have to schlep a hose into your MH either.
"Most" bathroom sinks in Class C's dump into the black tank. All you have to do is run the bathroom sink to fill up the tank. When I am at a dump station I can fill that tank up with clean water from the sink to get in a clean water flush in no time flat.
And you will also be surprised how quick it takes to run the water in the sink to fill your black tank. Will make you think twice about washing up, brushing teeth in the bathroom sink if you have a large family. THAT is how black tanks fill up so fast. :W