You guys are making this way too hard.
Hook up hose and close black tank valve.
Turn on water and go inside RV. Check the monitor panel every few
minutes.
I do this after first dumping the black tank and it usually takes 10 minutes or more before the monitor panel reads full.
I then go pull the valve open and get a really good flow to rinse.
Sometimes I will even do this twice. Using the campgrounds water doesn't cost anything extra.