If it was mine , I would just use the simi-gloss black vynal tape stripe.
I bet there is a company around you that can get it and cut it to the stripe width you want.

But if you prefer to paint it : use 3Ms blue vynal masking tape it comes in 1/16", 1/8th", 1/2" widths.
I would use the 1/2 " as it be easier to pull a straight line with it .
also make sure you use a quality masking paper so you dont get thinner /reducer burn through from spraying your color.

SprayTech