Late post, but i came here to find a solution.
Another way i found was to turn on hotspot from the iphone and do all the updating via itunes through a laptop. The laptop will of course be using the LTE connection on the iphone.
If you need to update the apps, just right click on the app in itunes and select update. Then sync of course.
I have only ever found unlimited 4G LTE while travelling in Croatia, which is why this problem came up for me. Apple more than likely needed to prevent outrage over fees from people not realizing apps are updating, and then couldn't be bothered putting in a toggle switch to turn the limit on/off. But likewise they couldn't be bothered putting the restrictions in when hotspotting, so yay for us (those with a laptop).