Been there, done that.
Had this exact same scenario on my '01 1150 GS three or four years ago. My solution was to cut the the shock bushing on the right side. I was fortunate enough to have a few mm of the bolt protruding from the swing arm once the shock was out.
From that point the bolt came out easily. I run Bitubo shocks and had to re-create the right side bushing by using the left side bushing as a pattern.
Hope that helps
"We can always make more money but we can never make more time."