I am sure you have come to the right place for help! Can you provide additional information? What year/model is your Airstream you are working on? That may make a big difference in the kind of advice you need. You might also take a couple of digital pics and post them of the part you are going to remove and replace.
I know when my husband replaced our entire floor he beefed up the frame by the door as it seems to be one of the problem spots.... If your channel and floor is anything like ours, the channel sits on top of the wood (I believe...) and the floor is bolted to the frame. It is a big job.... many folks have made repairs in sections, however... I would check the search function in the blue toolbar above and key in partial floor replacement or something similar and see what you get! It will give you threads that have discussions on floors.
Here is his thread on floor replacement: you will have to scroll through a lot of pages, but he has good pictures that explain what he did...
Mrs. NorCal Bambi (traveling in S Tardis)