hugh.
it would help to know what type of ending your going for.
maybe a song example from you tube.
i do custom endings sometimes.
many ways. fades/one shots/drum solos at end /all sorts.
what are you going for.
a good way to experiment is to start a new project in biab or rb, and just experiment with a drum track.
what i do for example is put part markers all over the chord
sheet in biab, load up a real drum trak, and test out various ideas. you could for example switch to a new drum sound for an ending. for example i just did that in a new song.
you can also build custom drum traks useing rd's as a base.
lets say you got a regular drum trak going in a song but want a drum solo at intro or end, or anywhere.
you can do that.

best.
oldmuso

my songs....mixed for good earbuds...(fyi..my vocs on all songs..)
https://soundcloud.com/alfsongs
(90 songs created useing bb/rb)
(lots of tips of mine in pg tips forum.)