I’ve fitted rowlocks to Wayfarers on three separate occasions (and two different boats).
First one was in a composite MkI which had wooden blocks in place under the side decks. I spent a lot of time sitting on the thwart pretending to row and ensuring that I got the holes in the right place. I put them as far outboard as I could without the rowlocks hitting the hull. However after a season’s use I had to admit that I had made a mistake, as the sockets needed to be further outboard. I subsequently had a capsize and lost my rowlocks, so ended up with a new set which included new plates, prompting me to improve their positioning.
For my second attempt, I made little marine ply wedges to fit under each rowlock plate; this meant that the rowlocks would be canted outwards slightly. matching the slope of the hull, and enabling me to put them an in further outboard. It doesn’t sound like much but the difference was huge- wish I had done it like this first around. Oh, and I also tied the rowlocks in with a length of thin line so that i wouldn’t lose them again.
(A couple of years later, I sold that W and got my current one, to which I fitted rowlocks, which I duly lost in a capsize. I am now on my fourth set of rowlocks and, yes, these ones are tied in!)