I like the short boss pipe solution but at the moment the pan connector disappears through a tiled floor which I'm going to have to dig up to find out how far it goes and what it goes into. It's a good job I've got some spare tiles.
To save digging a 15m trench, I need to connect the waste from washing machine and basin into the pan connector for the toilet (ground floor and solid floor). I know pan connectors with an integral waste connector exist but this would reverse the fall or need stilts for the washing machine...