Steve, Eric...
The main problem here, it seems to me, is the RF link. In most cases this is likely to be unidirectional so the possibility of a handshaking system such as Eric proposes is not really on; unless of course you have a complete transceiver (RF) at both ends. It would more than double the link cost too.

However there are high reliability systems for data transfer over RF links such as the AX25 or Pactor systems favoured by the Amateur Radio community.

With the advantage that the code is Public Domain :)

regards,
dm