They seem to be everywhere around the west wales coast.

The only good thing is that in fine weather there are usually several dive boats operating who will assist if neccessary.How much tide they can cope with I dont know.

Visiting the area this year I came to the same conclusion as you that Inshore areas are not sensible in the dark. Its hard enough in daylight avoiding them.

Any shoal area of rock seems to attract them but you cant rely on that others seemed to be laid completely at random ie areas where there are no sea bed features noted on the chart.