For the other hardware, I chose 5/16"-18 t-nuts to go on the underside of the rack (the kind with the prongs, so they dig in to the underside of the rack and stay there). I also used fender washers and lock nuts, and the bolts are 5/16"-18 x 3/4 inch. I intended to use thumb screws so they would be "quick release", but Lowe's only had them in 1 inch length, which was too long for reasons to be revealed soon.
Removed rear rack. Here is where it could have been done slightly differently perhaps. We removed the metal backing on the rack and drilled the holes where we thought best.
Then, of course, drilled the holes in the ActionPacker.
Next, the t-nuts went into the holes in the rack. Once they were partially in, I used the bolts and washers to crank them down so they are set in there good. Here is how it looks - the four silver looking holes are the new holes with the t-nuts.
For some reason I thought it was a good idea to remove the metal plate on the underside of the rack before drilling the holes. If the holes had been drilled a little more to the inside, they would have cleared the metal piece allowing for a longer bolt. Not a big deal. See the silver piece of t-nut from the underside after installation.
Another shot of the underside of the rack.
Hundreds of pennies were spent on the mounting hardware.
I may still go with the thumb screw option - these bolts are 3/4" long - attach or unattach with a 13mm socket in about a minute.
And now I am ready for Action. I just need two matching padlocks for the handles.