A Theology of the Apostolos?

We are very accustomed to reading theologies of Paul and sometimes even theologies of the "Gospels". But I don't recollect ever seeing a serious theology of the Catholic Epistles as a unified corpus. What is more, the Catholic Epistles and Acts comprised a literary unit in the Ancient Church called the "Apostolos" and you can find manuscripts that contains these writings and lectionary readings based around them. Part of the problem is, as David Horrell states, a perception that the contents of the Apostolos, "do not constitute a collection of texts with a distinctive and closely shared theological perspective". But is this really the case? Is the theological complexity (read "diversity" if ya like) of the Apostolos no different from the complexity within the canonical Gospels, within the Pauline corpus, or within the Book of the 12 Minor Prophets. The Book of the 12 is probably a good example. If it constituted the one literary "corpus" then it was probably meant to be read synchronically. Should we read the Apostolos (or even just the Catholic Letters if ya want to leave Acts with Luke) the same way as a distinct literary unit that comprises a mutually interpetive collection of texts? Some unity of the collection might well be inherent like elements of christology and praxis, but some elements of unity would be constructed when these writings are read as a literary whole. I think this is a good Ph.D thesis in the wings waiting to be done by some brave soul. A canonical reading of the Apostolos as a single corpus with its own theological texture!