Thanks to Rick, Warren and Mark for the feedback, and a happy 4th July to all the american members here.
I got the undersides masked and sprayed the PC10 today and I'm happy with the results...

The ribs are still not quite as good as they maybe could be, but I'm happy with them...room for improvement on the next one though.
I'm very happy with the wing undersides though. When I masked off the undersides, I cut the masking tape to shape using the wing itself and then inset it a little to allow for the wrap around of the PC10 and it's come out very nicely - I'll certainly consider using the same method for any Nieuports I build in future.

Now onto the struts etc....
Thanks for watching,
Ian