Repairing Delamination on 5th wheel exterior?

About a month ago a friend of mine noticed some delamination on the upper portion of the side wall of his fifth wheel, a 2006 Saber. After some investigating by both of us, it was discovered that the lap sealant in that corner had a hairline crack and the EPDM membrane had about a 1/4" long tear in it where it was pulled over onto the wall and stapled, (definitely a manufacturing defect) which allowed water to enter and trickle down into the wall. Something that can never be seen unless moldings and lap sealant are removed. A plan was put together to perform the repairs ourselves. That plan being to cut out and remove a two foot wide section of the wall from top to bottom, make the necessary repair and replace that section. After the job began, we found that the delam had started to take place on the rear wall also. After replacing the side wall, we ended up removing the entire back wall, made repairs and replaced the back wall. It came out so good that he took it to a local shop to have the entire fifth wheel washed and detailed. We've had many complements on the job. From start to finish took 3 of us four full days and cost about $300 in materials. He never checked with any RV repair shops but I'm sure it would have cost $3000 or better. The job was not at all bad, just labor intensive, and that's what makes it so expensive when done by a shop.