While I was removing the pieces in order to do your heat soak fix, I noticed that there is a line for hot water that runs through the bottom of the area where the cabin air tube runs (inside of the cowlings and your new center insulation over the foam block). I had driven the car and so the hose was VERY HOT. I am going to wrap the entire cabin air tube and see if maybe that prevents the hose that is actually inside of the area from transferring heat to the tube as well. You may have already found this, but I figured that I would share just in case you had not.
This has to be one of the most useful threads in all of Lotus Talk. Thanks for keeping us up to date on your findings. I look forward to dramatically cooler air temps. I might have to actually turn down the AC if this works well!!!