Having flutes, clarinets, and trumpets is pretty much required for SR. Do you want to have to read a piece with no one playing melody for 8 or 16 measures?
That's where the line is IMO. If you have a TON of clarinets (or trumpets) and none of the other, you can have kids cover the parts. Other than that? I'd be hesitant. Go to a festival and earn a trophy instead.