I would just say make sure the bowl is big enough to keep water for that amount of time... u dont want too shallow of a dish or it will evaporate. I think 2 weeks will be fine as long as there is water there for him to get moisture from. Although u wouldnt want to let it go for any longer than the 2 weeks.
Anyways thats my 2 cents... if u dont feel comfortable doing that just have someone come over and change the water after 1 week so it only has to be done once... I know they can go 1 week fine without a water change