I vote for a Blue Spot jawfish!
Oh, that's not on the list. Can't hurt to try.
If you are only adding one more fish, make it a good one. You could have 2 neon gobies for the bioload price of one six line wrasse, and 4 neons for the bioload price of one Kole tang. Therefore, if you get the Kole you have absolutely no more room. If you get the Neon then you at least have some room for future additions (Blues Spot) and or growth of the existing fish.