Only good choice I know is an automatic feeder set to go 1 or 2 times while you're gone.
(You'd need to feed frog bites).

There are cheaper ones than this, but most feed measured amounts from one reservoir on a cycle.
It would be easy to overfeed if it dumps too much out daily.
This one has 28 slots, most of which you can leave empty for skip day feeding.
http://www.thatpetplace.com/pet/prod/211008/product.web

Other than that, I can only suggest feeding well before you leave.

~Mac