Per client request, can you leave dogs home alone overnight?

Hi everyone, I had a meet and greet with a potential client and her three dogs and it went great. Everyone got along and we all wanted to move forward with, technically, an "overnight" dog sitting position. The potential client mapped out what she would like me to do for her dogs and misc. caged animals. She told me I did NOT have to sleep there overnight. Of course the dogs would bed fed and let outside for the bathroom, but I did NOT have to sleep there.

Is this legal? I live in New Hampshire.