What did you have instead of the sissy bar that comes with all Standards and Tourers? One of those aftermarket "solo bars" that spans between the "ears"? I have removed my sissy bar to add and, later, remove a bracket for my CB antenna. I didn't have to loosen my fender rails or remove my shocks to do this. It does take a bit of muscling to squeeze the sissy bar legs between the fender rail ears.
Thanks Pete! Are there any precautions I need to take while removing the shocks?
Yes, you need to support the weight of the bike so the fender doesn't fall down on the tire. I do this with a motorcycle jack under the engine, with an adapter.