Combine a low power XBee receiver with high power XBee transmitter in a model rocket
I guess you are not trying to get range >1km, right?

Are you really sure you need telemetry? Logging data into microSD card is way easier &amp; more reliable. microsd card can survive even the most horrible crash.

If you really need to extend range, I would suggest directional antenna on ground receiver with servos to track rocket. That would be very fun and will extend the range much more than 50mW transmitter.