The RCSC specification does provide some guidance for reducing a bolt’s shear capacity when a loose filler plate is used. My understanding is that this a way to account for the bending loads on the bolt. I think this is somewhat analogous to your situation.
You can download the specification...
Here's how I visualize it:
Picture two U-shaped plates held together by a single bolt. The upper plate is connected to rigid support and the lower plate is connected to a load. The bolt connects the flat portion of both U-shapes to each other and is pretensioned.
The pretension load in the...
