Greetings, jubya.
Since no one else has said anything, I'll chime in here.
Not having an airbrush is a liability for those German spots. Even then, they're tricky to do.
One suggestion I've read about--but I've never tried it--is to paint the fuselage with the darker "spot" color. Let it dry, then attach little tufts of cotton balls (and they would have to be little!) in the proper spots. Then paint over it all with the lighter background color. Then you remove the cotton.
I suppose you would attach the cotton with a tiny drop of white glue and hope it doesn't come off during the process. White glue cleans up very nicely with water..
Instead of the cotton, you might try little bits of poster tack. Again paint the darker color. Place itty bitty pieces of the tack. Then paint the lighter color over all. The poster tack should give you the soft edge you need.
A third option is to cut a mask from paper. Paint the lighter color, then tack the mask over the top, keeping it a little above the surface. You could use poster tack for this or rolled up bits of masking tape. Then use a spray can to paint over it. Again, this should end up giving you a soft edge
Be sure to let each coat dry before you move on to the next step.
Again, I emphasize that I haven't tried any of these methods cuz I do have an airbrush, but I haven't attempted any spots for a while and no doubt am out of practice.
Maybe someone else has better ideas (I hope!). But whatever you decide on, good luck with it!
And start saving up for an airbrush. I only have a Paasche H model and one of their (Paasche) cheaper compressor; no air tank, no regulator. Nothing too pricey.
And maybe I should take my own advice and start saving up for a better system!
Again, good luck!