http://www.lindyfishingtackle.com/ti...amerdriftsocks
Here's a good little article on rigging a couple of socks to slow you down. I think this would probably slow you down more than you're looking for but it's worth a shot.
Have you tried back trolling those spinners? That may give you the speed you're looking for even though a few folks think that method is outdated.
Either way the drift socks are a great addition to any boat and I don't go anywhere without mine.
Good Luck