In my experience, tuberous begonias can tolerate a bit of drought because they are like succulents.

Alot depends on how hot it gets between waterings, I should think.

I take Fine Gardening magazine, and this newest issue has a great tip from a reader. She cuts old tee shirts into strips, twists the strips into ropes, wraps the ropes in saran wrap, securing them with twist ties or twine, leaving about six inches of the cotton exposed on each end. Then she fills a five gallon bucket with water and sets it near anywhere from one to four pots. She puts one end of the wick into the water, and buries the other end in her pot. (Multiple pots, multiple wicks.) She says it will keep plants moist for up to a week. I'm going to try it. This sounds like a possibility for your cabin situation.