So, is there water in the trays and the plants sit on top of the perfed grid?
If so, you can increase the wet surface area by adding pebbles to the lower tray.
Good idea on the perfed tray to keep the plants up above the water.
A cheap humidifier from the drug store might help you with the hottest parts of the day, too. In winter when you have the heat on at night it will be good for both the plants and you.