I think loosening the front mount really only serves to lessen any clamping force the frame rails may put on the rear spacer from slight variations in rail parallelism.
The only time I fooled with my rear spacer I had to loosen the front anyway becasue I was pulling the transmission and had to tilt the engine up to avoid pulling the swingarm/putting it back. I needed to keep the bike a roller for moving multiple things around the small garage. So it was a moot point regarding the rear spacer removal, but it may have helped. Maybe a little.
Merritt Island, FL
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