I have the same thing by X-treme and it maintains humidity for at least a week. I took out the foam inserts and put in some cedar scraps so the stogies would think they're in a real humi. Honestly, I don't know why I even bother with a wood humi and beads; I should just get a larger X-treme or whatever (they all look and work the same). They're low maintainence.

Occasionally, I put a few drops of 50/50 solution in, but mostly I just squirt some distilled water on the foam. You could always bring a small container of distilled water if you think you'll need it. If you only use 50/50, eventually it won't work.