I do not believe this will work. Once the other fuel line out of the T fitting is plugged after fueling, when the engine runs the muffler will pressurize the tank. But, go to full throttle and pressure will keep building up in the tank. Now go to idle and all that pressure in the tank that cannot escape through the vent tube because of the check valve will flood the engine right away. There is no way you will be able to get the engine to run correctly with a check valve.

To avoid filling the muffler, put a break in the muffler line that can be accessed from outside the cowl and disconnect it, fill the tank, then connect the tube back again when done filling tank.

Tom