However being a guided rocket, you should have a relatively good idea of where it is, ya? Especially if you can launch near a wind profiler which updates with 5 minute upper-atmosphere wind data, you should be able to compute a pretty close trajectory from the ground even with wind correction. If it's a guided rocket and you have two way communication with it, you might even be able to update it mid-flight with current wind data and let it correct it's own flight - would be an interesting way to test your navigation algorithms actually.

Anyway my point is (hey I'm into this stuff too, my mind tends to wander on cool tangents sometimes) you should have a pretty good idea of where this thing is going to end up as it moves. Assuming you don't need +/- 1-2 degree accuracy (which you won't, your antennas will be wider than that) you should be able to track it with your ground station very easily. Unless something goes catastrophically wrong there won't be super-rapid changes in it's ground relative position so just put a lightweight ground antenna on a semi-quick motorized base, tie it up to what should be a simple tracking app (hell I can make a perl script to do that), and you're set...

If you really want to get cool, have it measure signal strength as it moves and adjust for the peak... But that's a lot more work. :)