If I still had my 4B running, I'd cut it if I had to do it in vinyl.
Or I'd buy a pre-cut stripe from
Graphitek
But what I'd be most likely to do (faster, easier, less expensive and actually fun) is mark it off and paint it.
Use a blue Staedler pencil or some vine charcoal (available at any craft store) to mark off your width.
Tape of the stripe edges with 3M fineline tape (auto parts store)
Back that off with some good (not cheap) masking tape as an insurance policy.
Bottom stripe, if you're really worried, you can use regular autobody masking paper.
Burnish all edges.
Then paint with Ronan or 1 Shot lettering enamel using a 1" foam brush.
The edges all flow together so you can barely see a brush mark.
Then remove the masking tapes carefully so the paint doesn't spatter.
Do that immediately after painting and be careful not to "snap" the tape, it can land right in the wet paint.
Don't do this outside in the summer or you will have a liberal sprinkling of gnats and skeeters in your paint when you go back to check it.
Don't do it in the evening in summer either, even in a garage.
Love....Jill