Lot of people have a friend that can come by to refill water drippers and throw crickets in.
How old is your cham?
You could get a misting system on a timer with a big reservoir and have it go off just enough not to use all the water in the bucket.
For feeding you could put a few cups (3 or so in diffrent spots) in the cage full of crickets. This would be better than throwing a bunch of crix in free range to last the 4 days. That way the crickets won't be loose in the night to bite your chameleon.