Are you sure its painted on? Is it just two narrow lines? You could try wet sanding it but you will have to go easy. You can also try lacquer thinner if the van has all original paint under the stripes. Did someone stripe it for a blend line (painted above or below the line?) if so you should touch them or it will show. You could try one of these even if its painted, they work good for tape stripes.
http://solutions.3m.com/wps/portal/3M/e ... 5F9HLJ3Kbl
But if the van has had those stripes on there since 2001 the paint under the stripes will be a whole lot nicer that the paint surrounding them so you still might have a pin stripe even if its the same color as the rest of the van, just a thought.
Good Luck and congrats on the new van...