we have em for weapons after all. just do the same for armor equipped. instead of electronics use leather belt
Unless something has changed from FO3, I suspect this won't be possible without NVSE.
...at least I am assuming that the weapon repair kits use the same basic script function as the alien epoxy from MZ, which relies on functions that exist for the current weapon equipped, but that no equivalent for the current armor equipped exists.
A similar functionality could be achieved by adding the armor repair kit to the repair lists for armor, but that is less simple nor as non-invasive an approach...