I don't believe it will work at all. how long has your friend had the maroon and clarkii's? because I don't believe that relationship will last long either. those are probably the two meanest clowns.
I have kept tomatoes and perculas (not together). but the percs are small and slow, the tomatoes are bigger and surprisingly a good bit faster. that is not a good combo at all. I believe the tomato would make short work of the percula, even if the percula was added first.