Frame Rail Rust

While attempting to remove my Espar from behind the drivers side headlight I noticed what seems to be some fairly significant rust in the drivers side frame rail adjacent to the subframe. I am certain that this looks like an area which must be a common problem for T1N's as I believe I have read of reference to this in the past.

What have others done to remedy this particular area as it looks to be fairly involved lowering the front crossmember to repair?

Thanks so much, Chip

PS: I will include pictures if I can get in there properly to do so

2001 Sprinter 3-t or T1N. I think it´s a combination of salt and somebody trying to use the frame rail as a lift point with a standard issue jack used to abuse. You know the one intended for curvature i.e. the specified lift points.
Wish me luck as I grind it clean and attempt to avoid fire and third degree burns welding in a chunk of tapered 3mm carbon steel.