I see a bigger issue to this set up. In really extreme weather you do not ever want to be unhooked while on deck. The usual set up is to have two teathers, on the D rings so you can go from anchor point or jackline to the next anchor point or jackline without ever being unhooked. If you have the rope strop on the jackline, it may not be in the place where you need it. If you add a second strop that you carry with you, it will be twice as long as a normal strop and the strop you are hung on will be double, giving you a lot more stuff to trip over. On my previous boat, I put heatshrink on a twing shackle that used to beat up my deck and topsides and made a lot of noise and the heatshrink helped a lot. You might do a combo of S.D.'s suggestion of a rope cover under heatshrink for more sound attenuation.