I had the same problem, I replaced 6" across the intire bottom of both sides. There is a lip or L shaped bend at the bottom of appox 3/4 inch for strenth, I cut 3/4 inch strips and butt welded tham on to the patch panel and then butt welded the patch panel in place as discribed above. You will have some pin holes and I used a light under the bedside to fined and file those. You can use metal to metal or fiber glass short strand filler to make sure there will be no holes. Go slow take your time, it is worth the effort.
