Assuming a proselyte in the US is sincere and already identifies with the Jewish people and already keeps the main lifestyle mitzvot (kashrut, 3 daily prayers, tallit gadol, tefillin, Hebrew and Torah study), what are the main practical issues he would face if he underwent conversion with an ad-hoc beit din as set forth in the Shulchan Aruch (hatafat dam brit, toiveling before three Shomer Shabbat witnesses, accepting minor and major commandments) rather than going through the RCA or other standard channels?
Marriage could potentially be an issue, but would he be permitted to study at most Yeshivas? Counted for a minyan at most shuls? Would his cooking be broadly accepted as kosher?