No. When I say I fixed my creaks, I did not strengthen the boat per say, just fixed the factory defects. The cause of the creaking were due to these defects: deck liner having defective overlapping excess glass touching bulkheads, no caulking between liner and bulkheads in many places, ineffective joinery work on settee, settee rubbing on bulkhead due to improper mounting, no caulking between bulkhead and deck with the two touching. A lot of fixes were just adding caulking. Some I had to cut into the liner to get to the defect to fix. Some I had to add material to strengthen the joinery. Some I had to actually join because it wasn't joined at all. Every single one of my creaks could have been prevented with proper supervision during the construction of the boat....Sounds like you have found these gaps and modified the boat to resolve the issue.
I did not stop the boat from flexing, I stopped the boat from rubbing two peaces that should not be directly touching each other. If a boat is built properly, it will not creak while it flexes. The problem is boats are built by humans and we humans rarely get things perfect.
I do not see my boat flexing or oilcanning as you guys like to call it when I am offshore, but I know it is.