I used the 24-85mm/2.8-4D on Sea&Sea with the NX Fisheye Dome + ER40.
It required a +2 diopter, or no diopter if I used it from 35-85mm w/ the macro switch to on.
I stopped using that since on DX it would give me 36-128mm, will probably go back to her on my first Full-Frame body in a few years from now.
It was better on Full-Frame, but you can still use it. Behind a dome port you will be able to shoot both big (at 24mm) and small fish (at 85). I would not use it behind a flat port.
I guess the the NX Fisheye Dome + ER40 w/ +2 diopter will work for you, but it would be nice if you could do the test with the SXER instead of the ER40 and a +1 diopter instead of the +2.
The hard part of it will be to find a zoom ring... Hugyfot rings used to be the same size as Sea&Sea ones.
Good Luck