Bill wrote:

I appreciate your comment! I'd feel better about using that approach
if the rest of the "box" looked rock-solid. The joist-hanger
approach will evidently add some structural support to it, and that
may be a good thing.

Of course what you do is your choice, but the joist hangers won't add any
more structural support than simply screwing or nailing the cross pieces in.
Joist hangers only hang the cross pieces, they don't add structural support.

--

-Mike-