Many Iowa Sheriffs are just sore over having their power reigned in. Before shall issue began, CCW's were something only cronies and campaign contributers could get. Now they can't "sell" the people their rights, and they are more than pissed off about it.
If you ask anyone from any state that transitioned from May issue to shall issue, they will almost all say that what Iowans are going through is an inevitable part of the transition. Your elected local officials were mostly a part of the old way, and they liked the old way. They like arbitrary power. as time goes on, new officials will eventually take office and the new way will be the only way they have known. It will probably take the better part of the next ten years before shall issue finally sinks in.
The resistance you are facing is also something many of us in Nevada are still dealing with. Here, we have two cities and a county commission dedicated to finding any legal loop holes they can to keep preempted firearms restrictions viable. They hate guns, but they hate having their power taken away more. Keep the pressure on your elected officials. Constantly remind them who they work for and who pays their salaries. Do not let up, to do so would invite your officials to make spaghetti out of your laws, no one would know where their gun rights began and where they ended.
The last thing you need is to have to have a set of rules that applies to Burlington, but changes when you get to West Burlington, and then change again when you get to middle town, only to again be different when you get to Danville, then New London, then Oh, wait, now they're different in Mt. Pleasant, **** now I gotta take the round out of the chamber because i'm in in Fairfield. But then I can put it back in when I get to Ottumwa, as long as it's not in the car.
My solution when local governments opt to ignore laws preempted by the state, and this goes for all states not just Iowa; A civil penalty for violation should be charged to the local government or institution that willfully violated state preemption. To make it even better would be to make a civil penalty payable to anyone wrongfully arrested and charged with a crime that is specifically preempted.
So the state doesn't prohibit lawful carry in a park, but Burlington gives the state the finger and arrests you for being armed in Crapo park on a Sunday afternoon. How would Burlington like to pay you a $100,000 civil penalty? Even better, lets say the arrest is one violation, then when charges are filed, thats a second violation, now you just got two civil penalties. I'll even take it one step farther. The officer who made the arrest must be made liable for 25% of the penalty, and for the charges being filed, the prosecutor who put their name on the indictment would be liable for 25% of the second penalty. Hit'em where it hurts, the coffers. I bet you would find fewer officers and prosecutors willing to put their lively hood on the line just because their boss told them to do something against the law. The reason these preemption violations are still happening isn't because they are without merit, it's because there is no penalty for violating preemption. Make it hurt.