time to dust off the old sextant again...
It's hard to believe someone hasn't already thought this through yet. Not only the maritime, aviation, military and automotive applications, almost every one life-and-death, but GPS has become indispensable to the surveying and mapping industry, amd there is a massive support industry in ground based transmitters and signal reprocessing.
Also, at these frequencies, it will only mean further crowding for radio astronomy. The pieces of the spectrum they have access to get smaller every day.