Lobster, I don't think you have to worry about cooling. I have an evinrude that purrs down to nothing if need be. Are you sure that 2mph is what it actually is? Sometimes speeds vary between boats. If your dragging flashers on the bottom you will know your too fast with the throbbing and not staying on bottom. If your spreading spoons across the thermocline I'm liking that speed. As you may already know if your catching bows and salmon your fast if all are lakers pick it up a bit. If line is too far back go to a heavier weight. A drift sock as was mentioned off the bow does the trick though if truly needed at a min cost. Hope it helps.