I saved all the old flooring panels from the "dis-assemble" phase. They were used as patterns for the new flooring. They were also used as a reference to double-check original measurements. The old panels also held impressions on the top and bottom of the panels as to the position of furniture and mounting holes. Using exact measurements is "key" to avoid problems placing the shell back onto the frame. I also "referenced" the old panels to make decisions on where to place grey tanks and plumbing below the floor.
Here are some pictures of finished wheel wells and the cutting of new flooring panels. I purchased the plywood from Lowe's, the "RV Superstore." I decided to use a good quality cdx plywood 23/32 inch thickness. I felt that it needed to be a bit stronger. The previous flooring was only 5/8 inch thick.
All furniture will be rebuilt anyway so I don't anticipate any problems with a thicker floor.
The four corner curves on this trailer were somewhat symmetrical. I used a simple method to figure a smooth radius curve. It matched the original curve very well. The rotted panels were missing some wood for tracing around.
The wheel wells need to be water tight. As I installed the new flooring I caulked the exterior seems on the bottom side. I also plan to use black "undercoating" spray on the underside of the wheel wells. The upper surface (green side) will be out of sight and be covered by "interior" wheel wells.
The trailer took on a familiar shape. Notice the new steel panel in front for attaching the shell. Planning well ahead is a daunting task.
I am having fun !