You should buy a piece of 1x2 foot welding metal and try shooting that. But the most important part is shaking for 2 minutes, not 10 seconds, not 30 and not 1 minute, but 2 minutes. It shouldn't be easy to do. Then spray it like you would anything else.
I'm not sure what you mean about you fixing the stripes. What I would of done is feather out the edge of the stripe, sand everything with 1000, spray base on the stripes, reclear the entire panel.