What type of and how many chameleons do you have?
No food for 2 days is no big deal ... but unless you have lights on a timer and an auto mist system ... you'll need someone to pop in at morning and evening.
I have a neighbor do this for us. Our lights are on a timer but I showed her how I wanted the chameleons misted and that was it.
Everything has been fine every time.
I would go as long as 4 days without worrying too much about food (unless someone is pregnant)
-Brad