On my very old Roland SP-404 you are able to make a sample keep on playing in a loop, while not holding down the key, the feature is called "trigger playback", please create that! And you are able to stop a looping pad by re-pressing it. Would be a nice feature.
You can trick BM3 into doing this.
Set the loop to “forward” then turn on the sustain pedal. However to stop the loop you have to create a “dummy pad” (with the volume all the way down.) that is apart of the same “choke” group as the loop pad.
Any midi note value NOT using a momentary trigger mode will also continue to loop the sample when it is in loop forward/alternate etc.