Yeah just get the biggest 5 string set you can find and don't use the top string.
Or better yet, go to Bass Strings Online where carries a bunch of singles and can even do custom sets with whatever gauges you want! Jason is the only guy I'll buy strings from, he will hook you up.
Build your own string set!
Be sure to register and include you are a talk bass member in the comments and he will set you up as a vip for special discounts automatically.