I have no such 'spray port connection' so won't work on my unit. However, appears you have a great solution for your unit.
When dumping at a dump station, if no hose to connect to black tank flush, it's doesn't get done until where it's possible.
Have gone for over a week camping in multiple locations before able to use the black water flush & no problems.
2012 Fun Finder XT 276 Toy Hauler & Harley Davidson Ultra Classic with Condor wheel chock
2014 Dodge Ram 2500 AT 4X4 Crew Cab 6.4 L Hemi, 373 gears, tow package, Rambox option, Revolver X2 tonneau cover, Equal-I-zer anti-sway hitch.