Forget the timers, forget the lights altogether. There's a real risk of fire, overheating for the animal, and other things. There's really no risk leaving it without heat as long as it isn't digesting and your house won't get below 50 F. Remember that they live in the wide world without guarantees of temperatures or scheduled meals. Their metabolic rate is about 20% that of a humans, so a week without food isn't a big deal at all, even for babies.
Make sure your last feeding is 3-5 days before you plan to leave. Leave at least two bowls of water in the viv in case the snake decides to pass waste in one of them. (This applies even if he's never done that before.) Turn off the lights, make sure the viv is secure and enjoy your vacation.
How old is your snake, by the way?