I think your choice of eel, tusk and puffer is a great one for that tank. I'd leave it at that, at least for now.
I have a Brazilian dragon moray, I think it is related to the jeweled moray. Mine is a very aggressive feeder. It is with a zebra moray, ~8" black tip grouper, 4" dogface puffer and ~5" Hawaiian pinktip trigger. I keep the eel very well fed, but have not had any problems with it trying to eat these fish.
For some reason, the grouper, who used to hide in the rocks all the time, is out and following the puffer around. If the puffer is resting (say on a powerhead) the grouper will perch on top of the puffer's head and stroke it with a pectoral fin. What's up with that??? This behavior doesn't seem to faze the puffer.
I have a juvenile niger trigger and blue spotted rabbitfish that also hang out with each other.
This is why I keep fish (sometimes with corals) and not corals (sometimes with fish).
