(From a previous posting)
OK, so all that being said, if you still insist on wearing a leash in the surf, IMO, it needs to be attached to the nose of your ski either directly with a breakaway device at the front of the cockpit or by a jackline that the leash can slide to the nose on.
This will (obviously) present the least amount of resistance to the waves. A hole can be drilled through the nose, then filled with thickened epoxy. When the epoxy has hardened, a smaller hole can be drilled to accommodate a 3 mm line to attach your leash or jackline.
I suggest 3 mm spectra or dyneema. Same cord I use for my steering cables. I would not recommend attaching a leash to the tail of your ski because the impact of the wave will most likely damage your rudder or rudder hardware.
I personally haven't tried this arrangement and only use a calf leash offshore. But to me, it is the only system that makes any sense in the surf zone. I wouldn't recommend this system for offshore use though.