RV Repair: Removing rotted, aluminum angle, upper structure

Question
    I have a Mallard Class "C" 28 foot Sprinter.  On the front sleeping area, over the cab, the floor board has become separated from the sidewall on the passenger side.  There is a gap that I've tried to caulk a couple of times, with only temporary results.  The floor board for the front bed is how rotted and the plywood is bubbling and separating on the right side, right where it joins the wall.

    Is it possible to replace this board without tearing both side walls off of the RV?  How would you suggest proceeding?

    I presume that when Class C's are built, that floor piece was installed first, then the sidewalls of the RV were put in place.  

    I was thinking about supporting the front corners of the upper structure with jacks, then cutting out the old plywood, then fitting in individual planks or pieces of plywood, supporting the whole thing across the bottom with a couple of cross pieces of aluminum angle iron.

Thanks!  

Answer
Hard for me to say, without actually seeing how it is put together. It sounds to me like your plan should be fine. Just decide what you are going to do and stick with it.
A lot of times on older RV's, repairs can actually make them stronger than they were when they were built.
Dave