Barb wire stretching...

Have decided to run at least 1, will probably be 2, barb wires above our field fence. After this 2 of the dogs will either end up in yet to be built pens...or put to sleep. Anyways...What's the easiest way to tension the wire? Will wrap/staple the end. Have a come-a-long. I used a pair of bolted together boards to tension the fence. Was a pain in the Arsenal but it worked. Is there some sort of contraption available for pulling barb wire? We have rr ties set in concrete every hundred or so feet.