Update:
I took a break from the side rack project in order to relocate passenger and rider pegs, figure out a new shift lever and brake pedal, and relocate the turn signals, all of these projects in
the quest for a comfortable two up tourer for my wife and me. (You may see some updates regarding those other quest-related side projects as well, but for now just want to give a quick update about the side racks/cases).
As mentioned above-- since previously available CB1100- specific accessories are now discontinued--I've been forced to go a custom route, and have therefore ended up spending about $350 on $1,000 worth of clearance-sale SW Motech Trax Ion side cases and Varadaro-specific racks to try to adapt them to my CB:
Note: one additional complication requiring a custom solution is that only left side cases were available for sale (no right-side case), meaning that I'll have to adapt a left-side into a right-side case.
As you can see in this picture I've cut off all the arms on the Varadaro side racks, leaving just the main hoops that hold the pegs that the side cases slides onto:
With the arms all cut off, the left and right hoops are actually identical to one another, perfectly symmetrical (the only thing that I need to acquire or fabricate is a bracket that the right-side case will latch onto).
What remained to be solved was a way to mount these hoops to the side of the motorcycle in a correct and secure orientation, and extremely luckily I think these may be the ticket:
(It's lucky that they made the genuine Honda rear rack with 7/8" tubing, since this means there's all kinds of accessory mounts for 7/8" handlebars that will fit it.)
I don't need the whole clamp as pictured above, just the hoop part that clamps around the 7/8 in tubing...
... and here's where they go:
I'm pretty sure these clamps are in the right location so that I can just use a series of spacers and bolts to attach the hoops directly to them.
(I did a test holding up the side cases with my wife on the bike, and I think the position is correct, though spaces are tight given the exhaust pipes below and her legs above, so until everything is mounted and we actually take a ride, I may not know if my luck has held, or if instead it's take deep breaths and shuffle back to the drawing board.)
Once the hoops are attached to the rear rack via these two clamps, then I can determine what additional brackets I may need to make sure that the side cases are secure and aren't going anywhere when riding the bike.
Please stay tuned for further updates as my quest for comfortable two-up touring continues...