I'm doing somewhat the same thing but with a small radio-controlled robot. I'll use the DTMF tone generator (UM91210, UM91214, etc.) in combination with an FM transmitter for the remote and an FM receiver with DTMF decoder on the other end. This combination allows the usage of 16 functions and is very easy to implement.
Also, you could try the MC145026 encoder and MC145027 decoder from Motorola that does almost the same thing. It has 16 functions (via 4 bit data inputs) and can be interfaced via radio frequency or infra-red.
If you want, I can send you the schematics.