Like you I painted my truck one piece at a time with a solid color using the base coat clear coat method. No issues. I actually started with the cab interior which is a metallic brown. At first I started with single stage paint and had the kind of results you fear.
Started over with base/clear and got a very uniform coat with the metallic paint. I was impressed how easy it was to fix mistakes with the 2 stage method and was glad I went that way with the solid body paint.