whenever i cook swordfish or tuna I do the absolute bare minimum.
which usually is a 50:50 of sweet balsamic vinegar and evoo. I just coat the fish, leave it for about 30 mins and than cook. Can't see how this would change much for the smoker.
Both tuna and swordfish are fairly subtle flavours and great texture.
For Cold SMOKED salmon. I use a 50:50 coating of honey and balsamic vinegar - this would probably work for unsmoked oily fish as well.
basically the vinegar is there to cut through the fish's own oils and clean the palate. The evoo and honey are to help the vinegar stick to the fish and add a little sweetness.
You might be thinking 50:25:25. Balsamic:evoo:honey would be good.
But evoo and honey don't work for me together :-)
I'd use one or the other. And use it as the spritz/mop during smoking as well.