How would you go about replacing floor and skirts when wall

The wall is partly over the flooring and partly over the skirt you can see in the photo. The sill for the most part does not need replaced. The inner skirt is completely under the floor. It is bolted to the frame and the floor. The skirt you can see is attached to it. It also needs replaced. I want to detach sill and wall frame from floor and outer skirt, replace floor wood framing under floor and outer skirt without taking the walls down.

Wonder if you might install a series of vertical 2X braces floor to ceiling a bit inside the walls to insure the height stays stable and doesn't risk warping or deforming inner skin panels in case there are areas that are more weakened than you can detect until you get all the way around the trailer's perimeter. Somehow your description of the skirt thickness seems unusually thick. What's the make of your trailer?

It’s 1960 Sun Cruiser. My husband wanted to detach the camper from the metal so he could fix the frame for me, but I am not brave enough. The trailer has the metal frame, “sound board”, 1 1/2” x 1 1/2” floor joists around perimeter and then plywood. The sound board, joists and plywood are bolted to the metal frame. The walls are sitting directly on the plywood. I want to lift the walls just enough to replace everything from the plywood down to the metal frame a section at a time. I have left the closet and the other cabinets intact and attached because I don’t need to move them just yet to replace the flooring in the back of the camper. I am looking for suggestions to temporarily hold / prop up the walls until I can set them back down on the floor. I thought about the 2x4’s on the inside, but the closet is still in the camper so that should help somewhat. I don’t think I can get to the floor if I used 2x4’s as braces on the inside. I was thinking of something on the outside of the trailer.  I can’t see the above picture because it’s blurry, but maybe something like what’s holding it up might work.