Cray -
Let us know if you've got bait stealers at night as well. Those turtles shouldn't be active then. And if you have identified an area or areas where that gar hangs obviously target it first. Every gar I've landed I've dropped the hot dog within 4 feet from shore. I let that line just peel off. Most runs are slow - a bit of line off, a pause, more line, a pause, and then more line etc. There is usually a long pause though somewhere and that I've determined has been the gar deciding to either eat that bait or spit it out.
Curious to hear how it turns out for it. IF you switch to live bait I would nostril hook the minnow or shiner.