How to vacation with chickens and ducks?

We plan on taking a three or four day vacation this coming summer and not sure what to do with our chickens and ducks. We have eight chickens and two ducks that free range all day. Let them out early in the morning and put them away at night.
Really don't want to keep them confined in their coop for a whole three or four days, we have my grandparents come check on our cats usually but now that we have chickens I'm not sure what to do. They can't come at night time due to poor vision so they wouldn't be able to lock them up at night or anything, plus it would be a burden for them to come twice a day.
I have suggested paying our neighbors as they're very kind and would probably be willing by my parents say no and say we'll just leave them locked up and have my grandparents come by and give them food and water. Problem with this is that around the time we'll be away we hit highs of sometimes 115 degrees or higher and I fear for their health.
Any suggestions? We have no other family to stop by except grandparents because the rest of us will be on vacation. We can trust the neighbors but my parents dont want to make them do it. Not sure of anyone else we can trust with them either.

 

Ahh sorry forgot to add this in. I think it's about 5 or 6 ft high and 8.5ft or 10ft long. Not sure as my dad built it. I feel as though it is not adequate space for them, they're always itching to get out or the ducks start picking on the chickens if they're not let out in the morning early enough. I don't believe my dad built the coop correctly and he keeps putting off fixing it (roof is just plywood with bricks holding the wood so it won't move) and there's technically no roost in there unless you count the measly piece of wood I managed to fit in there (not 100% secure, but it works for now). There is a ledge where it was planned to put a nesting area but so far it's been left as it is. It seems too small for 8 chickens and two ducks to stay in for a whole day, so that is why we let them free range from early morning to when it gets dark.