I have two of these planes and to solve the problem of the upper wing brackets I had new ones machined using 6061-T6 Alum. one peice and with a larger radius also at the cabane mounting point. I also made it longer and added two additional mounting holes. If anyone is interested, I have some extras.

I will post a pic here on Monday.

The pic is decieving. the long section looks thin but it mics out the same thickness as brackets supplied by GP