So I managed to spray on the wash coat, it went pretty well...
I need to find something I can use as a measuring/dispensing cup that won't dissolve in lacquer thinner.
The spray gun is nice, I was using a 1.2mm tip to spray diluted sealer and it went well.. the gun has a knob to control the spray pattern (narrow/wide), and I was able to get anywhere from a 2" spot to about a 6-8" fan.
The spraygun I got came with small tips/needles, in 1.0, 1.2, and 1.3mm - primarily meant for auto finishing, but a 1.0 to 1.2mm nozzle is recommended for stains.
For something like oil based paints or latex, you'd need a much larger nozzle - the particles of paint are larger.
I have the box fan on now, blowing air out the window to clear the fumes.
I'll sand the wash coat tonight, and then tomorrow I'll spray the stain.