Ryanharland
Member
Found an all in one Bluetooth, S/PDIF RCA preout interface kit called a streamblue that you plug the current steering wheel kit into. Not bad for £400 just a 4 month waiting list for them..... 
https://navtv.com/products/NTV-KIT510/streamblue.html
https://navtv.com/products/NTV-KIT510/streamblue.html