You're right, not only that 'U' would be pretty wide but it's base would be cut by the upperwing cockpit cutout...
two stripes that angle outward from the leading edge.
They also seem to angle inward...
So as a conclusion, the only way it would seem to be angling both outward and inward at the same time would be:
the most likely markings are two chevrons
...pointing towards the leading edge.
