Are you saying you want no in-text citations, just for the author-date format just to appear in footnotes (instead of the usual footnote format)? What about the bibliography - how is that to be handled? Also, is this format to be used for a particular purpose as it seems quite unorthodox. Note, that style guidelines and preferences are dictated by respective publications (e.g., journals), academic disciplines/purpose (e.g., research paper, thesis, dissertation) – in which case you should confirm what is the proper style to be using.