this in my opinion would be the best advice i could give, its cheap to make and easy, i myself will be doing this in the near future, not like im gone allot but if i have to go just set it up quick and leave.Just setup a float valve with a large reservoir of RO water, or a low PPM nute solution.
I've been gone for an 11 day vacation through mid flower and I came back and plants
looked pretty good for the most part. The nute solution was very low as I simply used RO
water in a 20g reservoir, but they were alive and not burnt at all, just a wee bit hungry.