You can avoid having to do time-stretching by putting in a huge tempo drop (50% or more)on the held bar or the one after it, depending on the song.
When you import it into a DAW, you'll have a nice long fade which you can fade out as needed.
BTW - If you build the tempo change into the BiaB file, and then import it into RB as suggested above, your new endings will also get the extended hold.
Last edited by boydbob; 06/30/16 05:26 PM. Reason: slight addition