Go easy on water usage. Don't let the faucet run for showers, washing hands, brushing teeth.
Since you're just going for a couple days use paper plates and if you have enough silverware, don't even wash dishes until the last day. Wipe the pots out good with a damp paper towel and you can re-use the pot. Grill outside.
Lights at night? If you're not using them, turn them off.
A furnace can drain the battery fast. Hopefully, you won't need it. Or else, sleep in the cool temps and run it to warm up in the morning.
Toast? Butter bread and use the frying pan.
Coffee? Use a perculator on the stove. It makes excellent coffee.
You'll be amazed at how well you can do! You'll be back for more of the same.