On winter days (water temp only gets down to about 60 here), I wear a full, one piece wetsuit with the harness over that, and then the PFD on top. Sometimes the PFD gets in the way when I try to clip in, but most of the times it is OK. I like to have the harness as close to my skin as comfort will allow. If you put it over the PFD, it will shift and bunch up and be uncomfortable the whole day. In warm weather, I wear just the Harness with PFD on top (swim trunks are optional )