Hi, about your "Quick" Question, I hope for you it will be answered many times...
For me, it razes more questions than answers...
Why the inner wing? what about the outside wing? what about the rest of the van?
How old is the van, how much is the value of the van, how is the condition af the rest of the van?
But most off all HOW MUCH RUST, outside, inside and underneath the van!!!
Even when you post pictures, this is a very difficult question.
Ones you start working, you will most of the time find more (hidden) problems.
I would suggest, try to find a (Transit) expert, on the forum, and let him have a look at your van first
Good luck