Carry a "Closed - toilet being cleaned" sign
Then take your time to carefully empty the cassette into the toilet. I find that wellies, rubber gauntlets, plastic apron, gas mask with pine fragrance filter, all help to make the task a little more pleasant.
Nope - wrong method. Too, too conspicuous and leaves you exposed to public scrutiny far too long.
Scout the vicinity carefully, Park MH as close to the toilet door as possible, check no-one inside, check again that no-one is watching. quickly open the hatch and drag the cassette out, scurry inside, do the dirty (smelly) deed and get out and away ASAP. If you have poor aim, might pay to take a bucket of water in as well so you can do a quick clean before making your escape.
You will know if you messed up and there was someone on the next cubicle. Loud gagging/retching noise followed by "Wheeeeeewwwww.Gaaaawwwd!!!! What bloody indian restaurant did you eat at last night"
One thing you haven't asked about is where to get fresh water.
If this scenario doesn't appeal, I suggest touring France. Use the aires where no-one seems to care that the same tap and hose used to delve deeply into a cassette is immediately afterwards, shoved deep into the tank filler to replenish the fresh water tanks.
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If you do choose to use additives, have a look at the green bottles rather than the blue ones. Green said to be OK with any sewage systems while the blue contains pretty strong sterilisers.
BTw - we don't use any chemicals and especially in mild climates, there is just no need, especially if the cassette is emptied every second day.
