I’ve experienced similar on a national trust campsite down on the coast, can’t remember the name of the farm but it was far more pleasant than as they say most portaloos. This one wasn’t much more than a plank / seat in an open roofed shed that could easily be moved as just pinned down. The rear was dug out by a machine and left a one tonne bag in there with a large bucket of sawdust to cover everything and worked amazingly well. The machine returned with his fork lift prongs on to replace the bag every couple of days and everything was recycled naturally on the farm. I would imagine, into a slurry pit for a week or three.
In my van I also use the separation principle. All number ones go into a one gallon bottle titled ‘Recycled Cider’ and for the other, I use a Cuprinol fence paint bucket with resealable lid. Inside I use Asda bags around a Stella box. So the worst bit of recycling is the cardboard which isn’t an issue to the worms. The seat is also my Earlybay tracking guage
Ozziedog,,,,,,,,,odour isn’t an issue with the resealable lid