I've not been able to disable trimming when exporting a Group as an SVG image with a transparent bounding box. Tried
sketchtool --no-trimmed --group-contents-only=YES as well as Sketch API's
sketch.export with same options.
Even within the Sketch UI, this seems impossible. But if the bounding box has any style at all (even alpha: 1 one would do), then the Group will retain its original size. Watch here: https://www.dropbox.com/s/cjzpoxo23h5m074/SVG%20Export%20Trimming.mp4?dl=0
Not being able to preserve the bounding box is making it difficult to accurately export the design. Hope there's something I've overlooked?