What type of smoker do you have and will it maintain a constant temperature? If not, it is not advisable to do mussels in the shell, they have to attain a certain temp to make the shell open and allow the smoke cure to get in.
lol.....have never tried smoked halibut.....but if it involves me loosing a nut....i will pass!!!!Shell fish in the shell has to be one of the hardest things to smoke, while I have done the sea food on the fire pit years back (DAMN GOOD) out Dartmouth way, the idea of in the shell smoking does make me think, HMMM.
But I would give your left nut for a "GREAT" feed of smoked Halibut in a creamy dill sauce!. OH YUM