Sludge/Pin wash color recommendations for light color aircraft

Use a dark gray. It's not so stark as black.

Straight black would create too stark of a contrast.
And, Great looking Val.  

Dark grey was my first thought as well but I figured I'd ask in case someone had a better idea.  Thanks ridleusmc.  The kit is an older Fujimi kit I got for a song and dance.

It was missing decals so I figured this would be a great way to paint my own markings for the first time as well as try a lighter color scheme

For pinwashes, I think it depends on how deep the recesses you are trying to simulate are.  A really deep recess can appear completely flat black, while more shallow recesses like panel lines do look better with a softer color, either a medium to dark gray, or a darker version of the color underlying where you are putting the pinwash.