The Sig RYan STA has been done before in CL scale, and yes there will be one battery for the unit the pilot holds and another battery in the airplane.

Look to see if you can get hold of a JR radio with Direct Servo Connection. We have them here in the USA and these radios can be used for CL scale without any special modification.

For documentation for the Ryan STA look at this web site:

www.bobsairdoc.com

Bob has some great pictures