No. I've seen customers only. Post an update where? Private campgrounds? Truck stop? Public campground?
The only reason I can think of, and it's a real stretch, is a concern that the portable tank is full of oil, chemicals, etc and not the sweet biological components we expect.
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2017 JayFlight 21QB
2021 Ford F150 SCrew 3.5 Eco, 157”, 3.55, Tow Pkg
TaftCoach turned out to have hit the nail on the head. The fear is that there is something not black water in that tank. Also, just happened to ask two local spots who have septic systems that get pumped regularly, so dumping is reserved for campers. Did find out that Camping World will let you bring in a tank and dump it for free if a Good Sam member. If not, it is 30 bucks, a good reason to join Good Sam if you have a regular tank dumping need.