I picked up some of these in the 4 inch size to slowly drag  on a swimbait belly  weighted hook in the cold water. They look great. Does anyone have any experience on the best way to fish these in the cold water? 

I think that they work good as trailers on spinner baits & chatter baits.   They aren't readily available in the KC metro area.  Stores that used to carry them are either out of business or carry different lines of plastics now.  My supply is dwindling.  I acquired them when the Boaters World store went out of business and that was a number of years ago.  I forget how many different colors I have.  The white/chartruese tail and sparkly clear/chartruese tail are what I use for trailers.

So, I don't know how well they would work dragging them on a swim bait hook but I know it wouldn't hurt to try.

I use em also on a carolina rig down here in Fl. great bait for what you're going to use it for.