Have you tried to spray not onto but UNDER the scales? I don't know much about a python, but for cobra I have once worked with, I got over same problems somehow. I believe cobra has smaller scales but anyway...
What I did:
I have put skin on the desk up side down, roll one end "up side up" so scales raised and sprayed enamel under them. I rolled whole the skin by pulling that end and sprayed under the scales until it became wrong side down on the desk. Pressed scales a bit . Let skin sit there then paint 2 tandy's supershene on top.