Try searching for a Mic1 tooling plate might have more luck finding something closer to home.

Regards plate on the profile then it would be a waste because if the gantry is bent then bolting to it just bends the plate to the same degree unless you shim it.
I've built dozens of machines using this size profile and I doubt you'll need to stiffen it up unless it's a very large machine with a very heavy gantry, in which case Profile is the wrong choice.!