I don't have enough experience/knowledge to tell you yes or no, my gut says no with the pcs. but with a tank that small I just don't know. Gonna have to wait for someone else to chime in here. Sorry.
Went back and read the first post again, unless the pair of tomato clowns are very small, you are not going to be support them in the 11 gallon tank for very long either.
The larger they get th emore agressive they will get. And in a small tank liek that it may cause more stress on them with the added aggression. You will also start to have a hard time keeping your water quality up as your bioload will increase with the larger fish. Bigger fish = more food.
Mor food = more that falls to the bottom uneaten. More food = more poop. etc. etc. etc.