I have the same size Rocna and in normal sand/mud bottoms it will break out once you get above it, like any other anchor. If the anchor gets fouled on bottom debris you're screwed, like any other anchor.

Here in the NE the water isn't very clear, and it's especially turbid in my home waters of LIS. So you don't know what's down there, maybe old chains or boulders, or other debris. I think your idea of a floating line with a spliced loop makes sense, but I think it would be wise to size it so the upper loop is at least 7 feet below the surface so it's not snagged by other passing boats.

1/4" Dyneema would be ideal, it floats even without an added float, and breaking strength is over 5000 pounds. A light color would be best for visibility. If the currrent is strong you could add a small float. If you make it approx. 12 feet long with a spliced loop in each end, you could attach it at the middle or one end, depending on water depth. You might also have another one that's shorter, maybe 2 feet, but if the water is that shallow you wouldn't need it. I've never seen a hoop anchor completely bury to the point where the hoop itself isn't visible.