If this is the kind of box you're doing, I don't glue the bottom in. It would be the same if you're making a box,putting in a top and a bottom, then cutting the top off, again I don't glue it in. The corners hold it together, loose panel just barely loose. I haven't been bit in the backside doing it like this. Maybe I'm lucky.
You don't always get what you go after,but you do get what you wouldn't have got if you didn't go after what you didn't get. Blaze Foley