For vacay, I suggest raising water level at least .5 inch over substrate. Keep sealed. By time u get back water should be evaporated.
I'm not sure if i agree with this statement. If the container is closesly sealed and he has a humidity of 75%, there's only so much more that the air can contain so I doubt the half inch of water will be evaporated and you'll come back from your holiday having a messy, slimey layer of algae on your container substrate.
In my emersed setups i've had the best result topping off the dirt with some hydroballs and letting the water reach till right under there