How is it hard to argue that she was involved accidentally? Is it not possible that Clover could have tampered with the stove, intending to kill, not a specific victim, but rather whomever used it next?

The fact that that person happened to be Lucy is something she could not have wholly accounted for, even by sharing a room with her.

[Don't write off the smol pink squad yet, guys, it's way too early for that.]

There is also still the possibility that Lucy intended to get caught in the blast, in order to make herself seem like a less likely suspect. I know this has been brought up before, and that it's...rather unlikely, but there's no reason to dismiss it entirely yet. She did say that she'd moved away from the stove to go find Miata, did she not?