The base coat has nothing to do with the final gloss. In fact the base coat will never be shiney after it sets up. The gloss is what the clear coat provides and, whether you are close or not, also has nothing to do with the final gloss. Like you found out getting too close is not good so you need to follow the paint manufactureres guidelines for spraying temps and distances. Straying to far from the guidelines only cause more problems.
The FINAL gloss is acheived through wet sanding and finish polishing of the clear coat. You probably could have wet sanded out the runs you had and finish polished the entire tank to get the gloss back.
This is a pic of my truck that was done two years ago with BC/CC. It was wet sanded with 800 then 1200 grit and hand polished. It has a nice shine...