I bought a Sewer Solution about 10 years ago, to dump into a sewer clean-out about one foot above the driveway at my house.  I sold it when we moved this year.
Three thoughts:  You need to have a pressure water source for it to work.  Do not use your fresh water fill hose for that purpose.  Have a lot of patience and water, fast it is not.
Larry
I had the same experience about 10 years ago.  I used it on a small fifth wheel with small tanks.  It worked very well slowly.  It would be a real disaster to try to use it if you didn't have an unlimited supply of fresh high pressure city water.  
The design uses water pressure and a venturi to both suck the tank dry and break up the waste to where it fits in the supplied 1 inch hose.  The hose you get with it is not very long.  I had to buy two extra hoses.  It looses effectiveness real fast if there is any uphill pumping to do.  
The whole assembly will take up a lot of storage space.
I don't think I could attach one to my Beaver due to lack of room at the waste valve.