I used the vinyl tape on mine and really like it. It would be easy to change colors someday if I get tired of whats on it.
I started on the door and matched the hood and cab to it. Stick the tape on the edge of the door with about one inch more to the inside, then unroll very easy (don't stretch) enough to cover the length of the door. Hold the roll with your left hand and slowly lay it down on the door, using you right hand as a guide.
You can get much straighter lines with more tape unrolled. Give it another try, use the damaged roll as practice.
As far as the magnetic stripe goes, if you can lay it on straight, you lay the tape straight.
Joe