Kind of thinking out loud...
Duplicate the group with effects..
With the duplicate group highlighted, choose Layer > layer Style > Create Layers
You'll then have a layer for ever style applied.
Hold Command/Ctrl and click the thumbnail in the Layers Panel for the Outer Glow to load a selection based upon its transparency.
Delete all the style layers and the duplicate, create a new layer and add a mask based upon the selection of the Outer Glow layer.
Result is a layer matching the size and drop off of the outer glow but you are free to add whatever you want to the actual layer.