At one of the venues I play, the room is long and thin, with the stage area in the middle of a long side.Not ideal,but there it is. The p.a. speakers are unusually placed at 2 metres height, level with each side of the stage, pointing towards it.Yes, it sounds a weird set up, but it works. The feedack is minimal, as the mics are not facing the speakers, which act as foldback as well as p.a.As they are flown, there are no stands to get knocked over, but often they could be safe in an ad hoc situation that could copy this.
Otherwise, as others have said, lacking foldback, which is often used unnecessarily, put the p.a. speakers at the side of the stage area, level with the frontmost mics, so that sound can be heard on stage. I try to get the cabinets up as high as possible, in order to send the sound over the audience's head, also it puts them out of line with mics.