You don’t have to take the breathalyzer test, or do the sobriety tests at the location where you were stopped. Those are mostly used to assess the level of intoxication, and to build up evidence to use against you in court. You will not lose your license in Iowa for refusing to do so. They most likely will arrest you and take you into the station.
Once you are at the police station, you have two hours to contact a lawyer before you have to blow into the machine there. That’s probably when you need to determine how much you had to drink and when, such as if you pounded a couple drinks or shots right at last call, your BAC may actually be higher than when you were driving. Your liver can only filter roughly .02 percent of alcohol out of your blood per hour. If you think you have a chance to get below .08, or even under .15 to be eligible for a deferred judgment, it’s best to try to contact a lawyer to delay the test. This all is meaningless if you were in an accident, or have a prior DUI. Also, if you refuse that test, you will most likely lose your license.
This is in Iowa, not sure about other states. The main point, when in doubt, call an Uber.