Frame Stiffeners and Longarms, Add Plate to Center?

I’m getting ready to install Barnes frame stiffeners and Rusty’s 4 link longarms on my 96 and noticed the stiffeners are cut out where the factory transmission crossmember goes, so the oem crossmember doesn’t get lowered at all.

My long arm kit doesn’t fit in the cutout, so I can either add some 3/16 plate to fill it or I can make the cutout larger. Adding plate would drop the transmission 3/16” and I expect would be stronger, but also more work. Should I add a piece here or stick with the Barnes design and make the cutout larger?

Pics:https://imgur.com/a/juSq8IM

I would plate it. I've done stiffeners on 3 of my XJ's. It's going to be stronger than notching out the stiffener that much to fit your cross-member.

Weld a piece on the stiffener before installing it, it won't be that much more work than notching it, IMO.