Map Layer/Channel on/off to controller

So I design my patches as multi-layered things almost exclusively, combining bass, pads, lead sounds, what have you . My goal is to be able to map to a button on my controller the functionality of switching a specific layer on or off - so I could "turn off" the lead layer when done with it so that, for example, it goes back to only playing the pad layer.

The obvious solution is mapping a button to the mute for the channel in question, except this causes a problem in that if the layer I'm wanting to "turn off" has any kind of release tail, muting causes it to abruptly die instead of trail naturally.

Is there a parameter in Mainstage that doesn't kill audio from the channel/layer, but instead just toggles whether the channel/layer is actively receiving midi? Any help appreciated.Thanks.