Maybe there are not any lurking piles of bricks, then. There are probably rusty nails or something, but maybe Merry can survive tetanus.
On the other hand, it's not too late to give up and try sleeping in the French classroom!
Except then she'd have to tell everyone where she was going, and they'd look at her funny, and she'd have to explain her reasoning, and worst-case they'd think she was right and they'd all end up sleeping in the French classroom, and then they don't have an alarm so people would just find them like that in the morning, and then she'd never get the stains out of her honor.
Maybe if she mentally recites psalm twenty-three or something. Maybe they'll find a payphone before she runs out of psalm.
"As long as we don't touch anything," she mutters, and then ducks through the hole in the fence.