I tip the rear of my plane approx. 20 degrees down when refuelling. The vent pipe is then the highest point inside the tank (Kavan tank shape) and you make the area where there is air smaller. Because of that it’s easy to fill the tank close to 100 %.
Depending on the shape and position on your muffler, the fuel that went from the tank to the muffler, will come out from the exhaust exit hole.