Auto-Watering Setup Needed

I'm growing outdoors and I will eventually need some kind of drip irrigation system to give them water over 7-10 days due to my absence. It gets really hot where they are and I usually water them when they start to droop which is every 3-4 days. I will be away for two weeks at a time so I need something to fill that time gap so that they don't die on me.

Any suggestions? Thanks.

P.S. Stealth is definitely a concern. I can't have a big container with a bunch of hoses running out of it.

Thanks. Now that I think about it, I might be able to provide some cover for a large reservoir like a 55 gallon drum or something like that.