I would recommend experimenting with a Poor Troopers' style setup where you throw a sacrificial lamb to an angry cannoneer if that's the section that's giving you problems. Poor Troopers used Rika but until Nanaly shows up everything in that stretch attacks relatively slowly or deals magic damage so a Bandit should make a pretty reasonable substitute despite the lack of Defense. Besides, it's total domination, so splitting the pressure matters more than actually winning the duel anyway. You can lose units and still get Joy it's just when leaks start or your whole formation collapses that it's time for tears.