I prefer to "pack my own parachute" when it comes to black tank rinsing. I probably am going to make a 1-2 foot length of hose with a vacuum breaker/check valve on it, which will ensure no foul water gets out, even if the tank valve fails.
Right now, I have a dedicated hose for my macerator pump's rinser, but it is a tad long, so to save space, I'm going to build a hose that is shorter, so I can just use a FW hose with it.
Personally, I like keeping the black tank rinser separated... and never connected unless I am physically there. That way, this minimizes the chance for accidents to happen.
