You only want to feed as much as they will eat on a small time frame, depending on their age. When they're young feed as much as they will eat. When they're about a year old they will slow down to every other day / every 3 or so days for a female. It's not recommended to leave uneaten crickets in the enclosure as they could bite the chameleon.
What do you mean you have them in a clear box at the bottom of the cage? Are you using the box to feed out of or to store the crickets full time? Either way I wouldn't feed the chameleon from the bottom of the enclosure, nor store the bugs there.