Hello

I have bitten the bullet and cut into the bottom of the wing skin. I used the dremel type tool with sanding drum to create an oval hole with bevelled edges. Then I used a piece of sandpaper over my fingers to smooth out the edges and create the shallow depression. I then added a matching oval of thin ply using medium CA. All I had to do then was sand the small edge to feather it back into the wing skin.

Next up I need to add a layer of glass to replace that removed by the cutout/ply.

Cheers
Tarquin