you might have luck with the "fu-manchu" dwarf. They need little tank space and are more passive, although they will eat what they want. You will have better luck with adding the lionfish last as the often view current inhabitants as equals (even cleaner shrimp) and may not eat them no matter the size difference. Anything added after he is established...fair game...and they remember too. So just because a fish is bigger at the start, the lionfish will eat it when he grows bigger.
They are a favorite of mine, but I won't risk my clowns. i am going to buy another radiata (my favorite) when I get my fish only tank
-Dr Marco :sfish: