I have heard of people using 2L pop bottles with a couple pinholes in the bottom and on in the top to slowly let the water drip out. Don't know if it will last the full two weeks though. If you got time until you leave then I would test it to see how long it takes to empty the bottle.

Alternatively you can always set up a pump on a timer but that will cost some money and there is always the chance of mechanical failure or flood.

I wouldn't leave them in hydrogen peroxide.