Hey JP on my current build I tried a wash with acrylics and it got better than with oils, but you have to work more precise, because you cant wipe away the excesses. But if you go slow on it and build it up in a few layers you have good control over it and if mistakes happen they aren't very obvious.
Brush painting?

Why don't you try it with an airbrush? (Though I thought your p-39 was airbrushed

) It's real fun

I just pick out the details with a brush.
Do you know the promodellers wash? I tried it on some scrap piece and it got real good. I'll try it on my TBM.
Keep up this great work