We are not going to go through the pain of tapping into the evap core. Most likely it will be a small closed system with a remote compressor and tank in the trunk. We do need to use that actuator arm though and I know of what you speak, I used to play with it.
Now for the complex part. Bonnevilles at least your generation use shocks in the back, with the springs resting on the lower control arm. W bodies have struts in the back, with the coil mounted to a bracket on the strut itself. Any idea if the newer gen bonnevilles have a new system or the same system you have? How about the caddies?
I need rear bags with a mounting brackets just like strut on the left, which is a rear strut. There is room there for the bag to be below the spring mount, but then there is the problem of the rear sway bar mounts, which is a whole different issue.
We are just hoping that some GM vehicle has the parts we need as OEM options. The quest continues.