Do you happen to know the dimensions for the Engel MU40 you have pictured? I can't find any info about that model online anymore. Seems like that would be a pretty good reference for the max size to fit on the slider (you showed you could go back, and width/height is still limited by door frame).
Pictured is not the Engel, that's the Costco special I had before Engel.
It is 24"x15"x19". I did not install the handles to make it fit. There's maybe an inch or two wiggle room height wise, otherwise this is the max that would fit.