The metal tray was too flimsy so I discarded it. I went ahead and re-did it all in wood (3/8 playwood for the bottom and 3 inch decorative baseboard for the sides) I did re-use all the wheels, tires and assembly.
It is a bit heavier but still easy for me to load and unload. I ended up doing L brackets out of 2x1, screwed & glued and the long gun cases fit great. I will add skateboard tape to the inside of the brackets so the cases don't slide off during transport.
One of the things thac I did not want was for the brackets to stick out when I did not need them. The brackets are attched with screws and wing nuts so they can be removed if needed but just rmoving one and folding the brackets against the side seems to be doing the trick nicely.
Last thing that needs, at insistance of the wife, is some sort of attachment/hitch to slide a big umbrella for those Sun-Intensive South Florida days. The only thing that comes to mind is a piece of PVC pipe but that woule be making something tacky even tackier.
Final internal dimensions are 34x14 and stands 15" from the ground at the top.
And no, it is not going to be repainted red. And it is painted hunter green because I like the color. And JD: It is a TACTICAL LITTLE GREEN WAGON