Can I permanently disallow OS upgrades on an iOS device? Is there a way to prevent OS upgrades on an iOS device, such that the user is unable to remove the restriction (without going into full "kiosk mode")?

We will be loaning iPhones or iPads to people, and don't want them making ANY changes to the devices, but we do want to let them use all the applications that are on the device. I see that parental restrictions will let me prevent users from adding or deleting apps, but there isn't an option for OS upgrades.

If I tell iTunes to stop doing updates, and then prevent the user from accessing the iTunes store, will that do it?
I've just checked the Apple Configurator, and there is an option to completely disable the ability to upgrade iOS.