So, now I had to reprime it with the airbrush, which is a bit slower but at least it's much more reliable in my hands. I don't intend to repeat my mistake anymore.
To get something more concrete and slightly more display-worthy I covered the clear canopy piece with masking tape. Then I traced along the lines with my x-acto knife and tore the excess crap away.
|It went better than my attempt at masking Stuka's canopies|