It's not so much that he'll starve or dehydrate given the system you have set up. Just remember that seeds can look 'fresh' and full, but be nothing but the hulls - and water can evaporate or get soiled by any number of things. Just recently one of the local vets I work with was presented FOUR birds that went 4 days like this when their owner died and no one knew for 4 days. They were near death themselves having become dehydrated when their water actually ran out/evaporated (you never when a bird will decide it's bath time and use the water up for that)
The main concern is boredom and feeling abandoned which can provoke behavioral issues when you return. Joey (which is actually pretty original, in 19 years I"ve never met a Joey) may become distant, aggressive (out of confusion, insecurity), etc..
If you have a way to set your t.v. to turn on in the morning and off at dusk it may help.
A neighbor coming in to do just this may be an option - and while there to talk to Joey for a minute and make sure water is clean.
There are many actual Bird Sitters out there - check with local "Pet Sitters" to find out - call local vets to find out if they recommend anyone for pet sitting. It's one of the fastest growing pet industries in the world. People don't want to give up their freedom to travel just because they have a pet that can't go with them.
And that's the other option: Get an easy to handle travel cage and take your boy with you. Airlines allow birds in a carrier that fits under the seat in front of you on the plane, but call first to be sure you meet their criteria, which is usually a vet check up just days prior and a paper to prove it
The actual 'travel cage' can go in cargo. I've done this multiple times with special needs birds that a pet sitter couldn't handle.
So you've got a few options now - do they work for you?