While you are getting the RF modules figured out you could start on the project using wires.Then all you will have to do is add the RF stuff later on.
Good shout, I like it and I'm on it Boss

I'm thinking two 16F684's SEROUT from one into SERIN on the other to LCD / or Communicator. With a push_button on SEROUT PIC to simulate the beam at this stage with an LDR / potential divider to trigger the 'SEND DATA' at night fall.

How does that sound?

Dave