I have a Canvas Windmill simple Mk one (A-frame) tent in canvas. The only fittings I have added are small eyes under the gunwale that are all but invisible that take a bridle rope round the hull. The tent can be erected in minutes, having velcro tapes to hold it on. It does lack room, but in fair weather (which is most of the time) I only have the front half up until it is time for lights out.
I have considered using a sail batten fitted into the rowlock holes each side to extend the middle section a bit (I didn’t want any superfluous fittings either), but decided not really necessary.