Eschew those doubts - drive them out - tell them "Out, doubt!"
Nah, it'll be fine. Ain't nothing you've drawn there that'll get so much as a chance to warp... and the 4" stock is probably overkill. That basic triangle is about as stable a thing as you might see without horses. :)
I do like the thought of lapping the t-beam's top member over the ledger... and ALSO the thought of adding skirting to the front edge to stiffen the workspace.
If you glue those brackets together, they won't EVER fail ya.
-- Tim --
Like nobody's laughing