Hello! Yikes… I personally would go ahead and replace the whole part, as it seems to be meant to help with body/torsion rigidity (i.e. I’d never consider welding that back).
I don’t know how expensive it is new, but you can find some available on eBay for well under $500 shipped. For example:
https://www.ebay.com/itm/38858203176...Bk9SR8K3q6_YZg
I’ve been meaning to replace mine, as I’ve once ran over a pretty big rock that ended up denting it pretty bad, but thankfully in my case the part didn’t give in and, more importantly, it protected everything else behind it.
Geoff