Dunno if there's something here that could be applicable:
https://aerpro.com/vehicles/subaru/subaru_forester_2013_2014_sj

 

Most of the info you need to retain the steering wheel controls is here. Subaru radio and radio wiring harness information

 

This Steering Wheel Control converter: https://www.amazon.com/gp/product/B00B4PJC9K/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1
Was what I used in my '13 and it works GREAT. A little tedious to make the wiring connections, but it programmed itself with no input from me and has been working for the 8 months with no hiccups. Even the steering wheel Bluetooth buttons work, although my head unit has a little trouble getting the commands right. The "Mode" button does work as well, but shuffles through the input modes on the head unit. I would like to dig into the Metra Axxess instruction manual and reprogram that button to "Mute".

 

metra axxess ASWC. i have it, it works

 

kingston73 what did you end up doing?

 

Wow, blast from the past. I installed a pioneer using a harness I bought from ae64. Used an Aswc steering wheel control unit and also installed a backup camera. Overall it wasn’t too difficult once I found the harnesses I needed, everything else was just time and effort.