scoofy parent
If you were trying to land on a specific site though, couldn't you drop down a dozen or so transmitters at the potential landing site? The assign them a location, and have them transmit the relative location to anything landing near them?
How would you drop them? Don't think a radio transmitter would survive a hard landing, so you will need a proper lander (with altimeter) for each transmitter. And at that point you can just strap your actual payload instead of the transmitter.