I would recommend to use 11.1 DS , upgrade to 12.0.2. After upgrade take a task to migrate DS to supported DS. PTC is recommended the same.
We took totally different approach. We upgrade to 126.96.36.199 using 11 DS. Now we are trying to update to 12.0.2 and then we will migrate to supported DS.
We also used the version of WindchillDS that comes with 11.2 per CS337415. At this point I don't see any compelling reason to find a replacement.