Occasional Overnight Sitter Needed For My Two Older Kids

Hello all. I am a single mama of a 15 and 13 yr old. I work full time and travel once or twice a month. I am hoping to find a part time mother's helper to take my kids to and from school and also stay with them overnight, make and prepare meals etc. on the days I am out of town. This would be ideal for someone that has a job already but that has flexible hours. Or maybe a local college or medical student. During the day from about 9-4 you would be free. For what it's worth, it would be somewhat easy since my kids are older and can take of themselves for the most part. I would prefer to pay a flat fee per night rather than hourly but that can be negotiated. Would also include feeding and sometimes walking our french bulldog. :) Also helpful if you have a car.