An update:
I sanded everything down to the primer to the point where the primer was really thin but absolutely uniform in thickness, then degreased it (again) with acetone, then I recoated it with multiple, fairly thick layers of the SEM paint using l-o-n-g, continuous strokes from side to side. Here is the result:
20170219_151850.jpg
It's not 100% perfect but a ton better than yesterday and probably as good as it's gonna get, so I'm happy.