Hello, new series III owner here !

I've recently discovered some rot in rear cross member, here's a couple of photos

http://i.imgur.com/J731OeT.jpg

After a bit of digging (with the larger hole in darker area)

http://i.imgur.com/VCfa5fy.jpg

Thoughts on this? Should I go down the cut-out & plate weld route, or just bite the bullet with a crossmember replacement.. I've seen there's a couple of somewhat straightforward crossmember drop in replacement with extensions that slide over the chassis..