I have mainly adult chameleons and a mistking on a timer. So if I'm leaving for 2-3 days (which I do semi-often) I just dump out any water in the drainage buckets, fill up the mistking reservoire, feed before I go, and leave. The lights are on a timer as well so I don't worry about their heat.
It depends on the age of your chameleon, but by 7-9 months it's normal for them to be on an every-other-day feeding schedule, and if they're totally full grown it's normal for them to skip 2-3 days. So I don't worry about food at all when I'm away with chameleons that at least 6 months or older, they do fine fed well on the day I leave and the day I come back.
If I have small babies or a sick chameleon I'll have someone come by to check up on them and feed, though.