Water Damaged Enclosed Porch

rhinoguy

Here is what I am up against. First, I am not doing the work, I need to talk to the folks who will and I don't like being stupid!
25 X 10 porch, enclosed about 40 years ago. Roof is asphalt, about six years, over about 3/4 of room, 4/12 slope. The rest is flat, rubberized fabric cover, same age. There are no leaks. At the edge of the roof water has seeped into the wall, 2X4's are water damaged, pine siding has begun to rot, was covered with Masonite product fifteen years ago. We have the Masonite off and can see damaged studs. Window headers are damaged (some), sills look iffy, wall headers look okay.
Can this wall be repaired from the outside by removing a section at a time? Can we build assmblies that can be pushed into place as damaged wood is cut away? The lady is trying like the devil to avoid pulling this down and rebuilding ($40K). The reason to attempt this approach is to avoid removing expensive Ponderosa Pine panneling on interior. I realize it will have to be knocked loose as each section is replaced.
Granted, this would require excess wood as studs wound up being doubled in places. And it would eat up many fasteners. But it would be simpler than stick by stick and hopefully cheaper. I was thinking about window assemblies (48") and wall assmblies (32").
The brick and block foundation is excellent. Interior floor quite good except tile, a minor point.