I have done this surgery and it worked out well.
I removed side panel nearest the cancer. I removed and replaced the rotted section of flooring. It was a challenge getting the new flooring under the c channel but easier than a frame off endeavor.
I was able to replace the broken anchor bolts through the opening in the wall.
I had to replace every thing from the left side of the doorway to the front ofthe coach. I removed the flooring from the wall to the first longitudal frame member, (about 16 inches).
Let me know if you need more help,