in the future as a general rule of thumb, I'd make it my goal if you don't have someone as nice as nico around to watch your pet, do everything you can to ensure your cham will have a nice environment while you are gone with the goal being his survival.
if he is well fed the first couple days, he'll be fine the next two, he isn't going to die
however a good idea i came across is to get a container or something crickets can hide in and then putting cricket food outside of this container, so they'll have to come out and he'll pick them off when they do....also make sure the container is not clear, you don't want the crix to have any idea whats going on.
and if you can't find a pet sitter, find a friend...and to help your cham out, make the work as easy on them as possible, how hard is it to vaccum out the bottom of the cage and throw a premade cup of crix in?
the dripper is a great idea, just make sure it drips slowly enough to get to that last day, another good idea is to make a dripper going into the dripper lol
I figure it would be pretty easy to go out of town for 7 days if you have a good plan and of course having someone pop in and check on them is always a plus
i know i'm more scared of my house burning down from a basking light that falls and doesn't put itself out...