It's possible to cross the sniper area with Yoko and suffer no damage. In End of the Road scenario, you can use Yoko's crawl to set off claymore mines without harming her. As long as the mine is set off while she is still in the crawling frame, she won't get hurt. Make sure the mine doesn't set off during her starting / recovering frame as she can still get hurt in those frames. The good thing about Yoko's crrawl is that it protects her from BOTH the claymore mines & the bullets. Remember that only the sniper's 4th hit actually hit your character. So, time your crawl so that Yoko's in the crawling frame when the sniper fires his forth shot. Have Yoko's back face the sniper and press R2, then when the timing is right, press R2 + circle button to crawl towards the door to the next repeat. Repeat this crawl method as many times as necessary to move to the next room unharmed!