We do have a new black water tank rinse that is easy to use, and I highly recommend the Swivel Stik RV Black-Water Tank Rinser w/ Flexible Extension # CAM40074 because like your current kit, you only need to attach a hose to it and you're set!
It is extremely simple to use and has a pressure-sealed valve so you can control the flow of water to the rinser.
I have added a link to a video review of this kit for you to check out so you can see exactly how it works. view full answer...
We do have the Hopkins Endurance Easy-Pull Harness # HM48138 you can use to splice into your existing wiring. I do recommend looking over the wiring first as you may be better off replacing the whole Harness # A35W42B if there is damage to any of the wiring. view full answer...