I've also experienced problems with flooding with the inverted engine (magnum XLS 52A). I had problems with it siphoning. I turned the fuel tank around so it will fit lower in the fuse. It stopped the siphoning problem but I have not ran it since.

I also had the covering wrinkle when I installed the rear stab. Then I tried to iron it out only to have it pull away and expose the balsa. I fixed this by adding some red and white striping over the exposed area and found it looked as good or better than original.

Hope to fly it after the snow leaves in the spring.