Good Luck down there!!! Hope to hear of success! You've gotten some good advise here from the guys. If you get an overnight rain this week check for some fresh tracks for part of a morning. Might help you get onto one's travel patterns. If you're sitting for 45 minutes maybe try some stands with few more sounds than just the 3 or 4 and maybe not quite as continuos as you are? The changes grab a cat's attention which can sometimes waiver. Just something to think about. I like to vary the volume on the caller up and down from time to time and keep your gun pointed at the caller. In those areas over there look for some out of the way smaller pockets of cedar thickets to call. Especially if they have water. That way you're maybe not hunting for as much of a needle in a haystack as with calling the big blocks of thick stuff.
Main thing I can think of is to just do your thing and don't sweat it too much. I've seen Iowa cats come to one or two sporadic series of calls and also come to almost continuos sound running and everything in between. Either way, cats are easy to call when in proximity, and even easier to kill than coyotes most of the time once they come in. It's just getting onto them and getting close that is the harder part in Iowa. You'll get-r-done I have no doubt!!! Good luck!!!!
