water collection in wing root

[alcladrv]

My -7A is parked out on the ramp with a canopy cover on it. After a rain, I get a fair amount of water that collects in the wing root area.

I drilled a 1/8" hole (subsequently enlarged to 3/16") in what looks like the low point in the bottom skin on the right side. It only drains about 1/2 the water. The water surface tension is impressive. After the level has gone down, it will drip slowly. But, touch it with the corner of a paper towel or absorbent cloth, and it will get soaked in short order. After removing the screws on the left side, water drained from there as well.

'til now, I've been able to park it in a hangar.

Questions: Anyone experience the same issue? How big of a hole can I drill in the bottom skin to ensure the water drains without compromising performance or structural integrity?

Thanks, Mike