I have the same issue on Telstra in Australia. My workaround is to use the application Modeswitcher. I have it setup to have the Data on 2G only when the screen is off and Auto when the screen is on. No more reboots.
I have just installed ModeSwitcher but I am unsure how to program your suggestion. I see "on startup", "on close" switchers but no such item as "screen on" or "screen off".