Goshen Holmes at DIY lettering helped us with the same problem, they have a dark blue that matched our 2003 dufour 40 very well, they only could make 6 foot sections as I recall , so it you want to do the whole stripe that could be harder, but we had a few bad spots we just cut out cleaned and replaced. Looks great! They also sell the late felt pad that makes install much easier, highly recommended.
The membership association for owners of Dufour Yachts