My preference for floats is a slip float, pencil style with bobber stop, but that is more for verticle presentations. However, if I were to "drag" one as you say (casting and slowly retreiving) I would use a small fly casting type strike indicator just large enough to stay afloat with the weight of the jig you're using. Cast, pause, retreive pause, retreive pause, etc. The slightest change in the indicators disposition, I'd be setting the hook. If that doesn't work for you I'm certain a pencil or quill type will work just as well. It would give you and indication as to when the jig finally settled completely verticle.