Nothing like an able assistant for testing
I was thinking about some sort of quick connect/release as well, but I didn't have a concrete idea, or actually... any idea. Mainly to be able to swap the box with a flat floor, to convert to a flatbed. I will need to revisit that when it gets warmer outside.
One way would simply be to install the flat floor and attach the tote to it with a few bolts with butterfly nuts through the tote's floor, but it would raise the center of gravity when the tote is loaded. But that might be the compromise I'd have to go with.