Fuel will not flood your carb. The pressure will always take the path of least resistence, which in this case is the air vent. Some fuel may get all the way to the carb, but only enough to prime it. And yes, with the muffler inside the cowl, you'll have to wait for the fuel to come out of it.

I prefer Fuel Dots over "Filler Valves" mainly because filler valves are prone to leaks, but also because it never fails that I will lose that stupid little probe that is the only thing you can use to fill it with.