Although two pairs is too much, you can always pair different species within one pair. You'll always definitely have to watch for fighting, especially within interspecies pairs, but it can be done. I know you are not looking for more than one pair anymore(very wise decision, by the way), but if you want you can pair your tomato up with another species.
They are correct, though, that maroons, tomatoes, and clarkiis are among the most vicious(I would put polymnus in with that group, personally...), so if attempting interspecies relationship, might be better with two calmer species or a calm female species at least.
If you are looking for a pair of the same species, I always love percs, they do great in carpets, and the patterns that are out there now(onyx, picasso, etc.) gives you great options with what you would like to accomplish.