I too commend you,and almost envy you on a great project,but I have been there before and know how much you have if front of you. If I may,can I make some suggestions? If you want to REALLY keep this unit then you must do it in the best and most worthy manner. (Notice I didn't say the right way?) There are many ways to fix or repair damages like this but only a few that are really acceptable. I have seen quite a few pictures of repairs on this site and others that are substandard at best,I for one would not use some of them off the truck. I have seen the pictures of the damage that you posted. You need to remove more of the campers siding than that to determine the extent of the damage. Most RV repair places that I am familiar with would only remove a small section where the damage occured. This is not adequate for the structural integrity of the unit.You must replace the whole member to retain the strength that it was originally designed for. Don't just replace the small pieces that appear to be damaged as you are not fixing the problem. An example would be " what is stronger: 6 pieces of wood 1 foot long fastened together or 1 piece 6 feet long that is not" I have built a LOT of buildings and such for the last 30+ years from homes to Hi rises in the SF Bay area. So you judge on how you want to do this. Just remember that should it fail the person that gets hurt may not be you.
