Well, I went ahead and got a couple of the Futaba Tx module cases.
The internal dimensions are:
Width 34mm & length 54mm
Zitron, If you are willing to make a PCB that will fit the case, I can send you one of my spare cases as a pattern.
A Tx only board could then be made to fit a Futaba, a JR or just a 'hack module board' for 9X etc.
As I said before, I'm happy to assist with board costs.
An SMD mount Atmega would make the board size a doddle, albeit more difficult to solder (not a problem for me as I have an SMD hot air solder station) 
This is the kind of thing I'd like...
http://blog.ckdevices.com/?p=119
What do you think Zitron?
Nigel.
