If its an old cooler, be sure to wash it out completely and scrub with baking powder. A brand new small sponge soaked then squeezed out completely will also work. 40 smokes is not a lot in a large cooler, You might want to use a tupperware or Target sells a nice snap lid food storage container for about $7.
The paper towel in an open baggie works well in tupperware. Dont bother with the type of crap your B&M will sell you for humidification(most likely PG solution). Stop in at Cigarmony or Heartfeltindusties.com and get a Puck or the new round bead container. Beads are much more reliable than distilled water and PG. :2