I think your tank looks very good. I agree on the background. Solid black would really bring everything out.
Small fish considerations: After the tang is returned.
-Purple Firefish
-Yellow Watchman Goby, actually any small goby
-Sixline Wrasse.
-Royal Gramma.
One of either of these will all go well with your pair of Clowns.
Keep up the good work.
Bob