I have seen the video too. What is compelling is the fact that using the hose fitted devices never realy flush beyond a bend in the pipe. So far my process has been to dump black, fill via toilet with a few gallons flush again(repeat until clear) put another gallon or two with enzyme..drive home. So far, so good...ready to go on next trip.
I have never explored in any great degree either of these parks, even though they are both 45 minutes from my house. I know of them, but not enough to say anything. I can say I know the general terrain. These are low rolling hills of the Catoctin mountains. They are all beautiful and can say you won’t be disappointed.