The alternative is to pay for a site every 5th day. As you say phone ahead to see if just emptying can be booked, otherwise book a night. If that is not possible it would be responsible to go home. Alternatively stretch your 6 days by using public toilets where possible. What about pee pots, they can be un-ostentatiously emptied in hedges without damage. It is chemicals and faeces that are the problem.In an ideal world I would agree. However what are the alternatives?
We can make our cassette last for six nights, but we want to explore Britain for longer than this. We don't want to come home after six nights.
Thoughts welcome on how fellow Wildcampers manage toilet dumps when their travel plans are not fixed
Not wanting to use that alternative is not a good reason to damage the septic tank that the public toilet may empty into. Yes Britain should be more like France. That is a real "big job".