Suppose that somebody took something expensive that belonged to you which you left on a bench and you saw them do it.
Within a Kantian or more broadly deontic framework, would it be acceptable to use physical force to stop them if they did not return it when you asked?
I think you have dissolved your own dilemma ethically with the caveat "...not necessarily do serious injury or harm". I no longer see a problem with universalizing the rule here. If others were to attempt to enforce their versions of what is moral on me, but in a way that did not cause any serious injury or harm, I think that would be an imposition that I'd be prepared to live with in order to allow me the later autonomy to be able to take small actions to restore what I consider natural justice without having to appeal to the state.
If you removed the caveat about doing harm to the person, the categorical imperative would be breached as you will have harmed a person motivated by your desire for property, but without the harm (or even without the intention to harm) all you are doing is acting to retrieve property which the law says is yours to take. I don't see how he fact that it is in someone else's hand at the time, or the fact that you may incidentally harm them as a result of your actions makes any difference. From a Kantian perspective so long as you do not intend to harm them the action is moral.
The maxim behind vigilante justice that involves action rather than mere prevention seems to be 'Everyone should enforce the moral rules for themselves.' This would scare me. Many people think they know what the rules of morality are, and I would not want them to impose that misunderstanding upon me.
I am pretty sure, given his notion of nations and stable societies Kant would prefer that we choose the maxim 'We should choose who will enforce the moral codes and empower them to do so.' If that means you have to tolerate theft right under your nose, sobeit, the State monopoly on violence is more important than your pique.
