Almost all RV sewer hoses will deteriorate from UV damage and need to be replace at least once when they start leaking over a one year period. We've done volunteering and found that a Rhino hose is good for four to six months at the most. Valterra is marginally better.
Use PVC. It will certainly be easier to maintain the slope you need.
As mentioned let the black tank get as full as possible before you dump. The longer between dumps, the better the materials will dissolve in the black tank. Be sure to use plenty of water with each flush.
You will probably have to sacrifice a short sewer host extension to build a connector on the end of the PVC, and likely need a couple feet of sewer hose to connect the PVC to the RV. I see many long term rigs with that setup.