Your dimensions really aren't big enough for an active humidification unit. Just by having the container of distilled water you could run the risk of having a high RH by evaporation. Beads are easy and will last forever if you take care of them, plus you can get a Lb of beads which is almost 3x the amount you need for about 30$. In my opinion active humidification should only be considered if you are pushing 8 cubic feet or more. I could be wrong but you can't go wrong with beads.
