As a human being, I wholeheartedly agree: 35 degrees would be far better, and 40 better still. It's tough just being outside for an hour when it's in the low 30s, never mind living outside.

Unfortunately, as one of the volunteers, I can attest to the fact that it's always a struggle to get enough volunteers to support even the current arrangement. Raising the cutoff to 35 or 40 degrees would dramatically increase the number of nights for which coverage is needed and there just aren't enough resources to support that.