Garmin AERA 660 displaying mode s
 

Hi All,
We've installed a Garmin GDL50R in our PA28 to receive ADS-B to complement our Garmin transponder with ADS-B 'out'. We display the output from the GDL50R on a panel-mount AERA 660 and the results are fantastic - for aircraft with ADS-B 'out'.
The problem is the nightmare that is the current Electronic Conspicuity policy from the CAA. Whilst we get all the commercial traffic, the Air Ambulance and the Coastguard, relatively few private aircraft have ADS-B 'out'. Rather more now have mode S as they replace ageing transponders. I'd really like to be able to display Mode S on he AERA 660 but without disrupting the good work done by the GDL50. I suppose we should also be thinking about FLARM and Pilotaware but I'm really hoping they will wither away.
A tablet is NOT an option. Neither are things stuck on the windows.
Any sensible ideas?
Thanks
TOO

I look out the window.