Update to my own post - sorry.
I thought there would need to be an aftermarket solution, but I looked at the 2013 and 2014 parts fiche online and it appears that stock parts can be used to do the conversion.
Looks like only the hanger changed from two bolts in pre-2014 to one bolt in 2014+. The bad news is it looks like it takes about $75.00 USD in KTM parts to retrofit the hanger and hardware to mount the older silencer.