composting loos cost nothing? You gona get the campers to spend a day digging the hole and filling in the last one - or maybe cutting logs for the sawdust? Come on!!
Taking a shite costs money, money thats not normally visable to people who pay their water bill by derect debit and just flush.
If I didnt have outside loos - let em come in the house and crimp one off.
Its all 'cash'