How the zero - phase filter without filtered signal truncation at the end can be implemented?
You can either gather more data at the end than you need for output, or zero pad past the end of your data with at least half the length of your zero-phase filter.  

If you can’t get data past the “ends”, and don’t like the artifacts from zero-padding, then you might try other reasonable assumptions (circularity, continuity, etc.) depending on your model.