It is not possible as it is now.
I have considered this before. What prevented me from doing it is JTV recording, as a time-shifting session can be started before current program started, so you can never guess the right location. Technically, it is possible for TS recordings, but I hesitate to implement it because it creates more unnecessary complexity and confusion. Having said that, if one day I find myself not having things to do, this might be something to add.