Considering the lack of a slice feature or Time Stretch the best option left is to actually import a sliced loop and then re organise it on the PLAY, actually a pure RANDOM Play Mode would do nice 
UNless I’m missing something?
You are not. Indeed it’s probably the best to prepare the samples outside of the play and then load them into a project on the Play. When you load samples, you have to define a folder where they are going to live.
This allows you then to use the Randomize Feature: Sample In Folder to semi randomize which slice/sample is used.
Using Chance would be another option. But as far as i know using Random Sample there, will go through the entire Pool (unless someone corrects me 
).
Not sure if you have seen this Sample Slice Mode wish list post, but it would help voting for this as a future feature for Play, hopefully it’s a feature thats in the works, it’s got a good number of votes.
The slicing feature would not only be cool for drum breaks but you could also create a sample chain of say, different chords progressions of a synth sound you like and use the slice feature to play these back via Play, another cool addition to this would be if you could say select a particular sample slice and be able to play it back chromatically, I should add this to the sample slice post.
Voted for it
You could load a small loop and adjust the start and end points. Then shift them around. I don’t think we can move the start and end points together though…