Hello there, Dirk.
It sounds, from what you've described, that you want to manage a number of iOS devices with an image containing the same content. An option you may not be aware of and may suit your needs is Apple Configurator. The following link is to the online Apple Configurator Help guide overview page:
Overview - Apple Configurator Help
Apple Configurator helps you deploy iPad, iPhone, iPod touch, and Apple TV devices in your school or business. You can use Apple Configurator to quickly configure large numbers of devices with the settings, apps, and data you specify for your students, employees, or customers.
You can use Apple Configurator to set a variety of iOS device settings, including:
iOS updates
Lock screen and wallpaper
Device name
Installed apps
Installed documents
Configuration profiles (including passcode policy, restrictions, Wi-Fi, VPN, and other settings)
Mobile device management (MDM) solution enrollment
You can also create a backup of the settings, data, wallpaper, and Home screen layout from one iOS device and restore it to other devices.
Here’s how you can use Apple Configurator to configure and deploy devices:
You can prepare a set of new, unsupervised iOS devices that you configure only once, then deploy. Preparing devices is a great deployment option for enterprises and schools that provide devices to employees or students for their day-to-day professional or educational use. See Prepare iOS devices.
You can supervise a set of iOS devices that you want to control and configure on an ongoing basis. Apply a configuration to each device, and then reapply it after each use simply by reconnecting the device to the computer with Apple Configurator installed. Supervision is an ideal option for loaning iOS devices to customers (for example, in hotels, restaurants, and hospitals), sharing devices among students in a classroom or a lab, or deploying devices for dedicated tasks (for example, retail, field service, or medical). See Configure supervised devices.
You can assign supervised devices to specific users in your organization. Check out a device to a user and restore the user’s backup (including all the user’s data) from another device to the new device; then check the device back in and back up the user’s data for later use. This works well in educational settings where students need to work with the same data and documents over a prolonged period of time, but possibly on different devices. See Assign devices to users.
There are also some great resources linked on Apple's Support page for Configurator:
Business & Education - Apple Configurator - Apple Support
If you feel this software will fit your needs, the download link for it is found here:
Mac App Store - Apple Configurator
Thanks for reaching out to Apple Support Communities.
Kind Regards,
Pedro.