"Symptoms of a Clonidine hydrochloride overdose may include drowsiness, lethargy, weakness, slowed heart rate, low blood pressure, respiratory depression, fainting, seizures, and even coma."
To me it sounds like a lot of other overdoses, with low chances of actually dying but that could result in some physical damages after that, and since failing an attempt takes a pretty big mental toll on you, I wouldn't advise it. And that would mean you'd be going by struggling to breath until you can't anymore. I can't imagine how horrible that would be and how panicked you'd get