Change your listing policies so that your handling time is extended to cover the period you're away. So if you're gone for a week, maybe do 10 day handling time. When someone buys your item, theoretically they will see that it might not ship for 10 days.
Since you cannot use the vacation setting, you could use the mass listing editor to add a note to your listing stating that you will be away the week of x and all orders placed at that time will be fulfilled by. People don't read listings, but at least it gives you something to point to if anybody complains.
When you eventually get around to shipping the items, it would be a good idea to send a friendly message to the buyers that lets them know their item has shipped. You could give them a professional sounding reminder of your delayed handling time that was stated in the listing.
This is assuming the goal is to not check your app during your time off, so that you can enjoy your vacation.
There is no guarantee that you won't get someone unreasonable. Most people are easy going, but unreasonable people do exist. But overall, it shouldn't be too difficult to extend your handling time and communicate with customers why their item was delayed.
If the above sounds like too much trouble, you could always end your listings for a week manually, and then re-list them when you get back.
