For a complete, no details missing, no doubt left, answer, It often comes down to one person. I was going to cut a slab of 1/4" steel 4 1/2" wide by 20 inches long to go under the bin, but! there were too many more questions around that, so, rather than ask again, I was just going to hold off to see what I could learn.
Thank You Harle and Jordan, but most of all Michael, for giving up your time and going to the trouble to present the details, with the invaluable photos.
I now know what to do. This detail will no doubt help others and helps to preserve a snippet of history. I like that the bins have a "self cleaning" feature.
I now need to ask what thickness the packers are under the two rear compartment items (open top bin and the kit locker) This puts this info all in one place for those searching in future.