I DID manage to figure out something useful this weekend!
If you have a San-T-Flush system hooked up to your Black-water tank:
After you dump it for the last time: dump about a half-cup of dish-washing soap down the toilet.
Hook up the water supply to your flushing system, and let 'er rip!
let it suds the tank up pretty good,,, the more water: the better.
Dump it again... and again... and again. Keep an eye out for when you've got all of the soap suds out of the tank, and your hose.
The term "Stinky Slinky" will no longer be applicable to you hoses!