I am assuming here that it is a temporary fix as card-board can be a fire hazard IF the the dreaded S5 overheat bug hits you.
Ok - so I've fit it pretty well I have to say. On top, its going from the very front, under the cpu/mobo, then all the way to the end. The bottom is similarly covered to the mod, without the bulge obviously.
Temps are 64° / 60°, so unfortunately it doesn't seem to have helped.
I live in a very hot country and during the day there's no A/C so room temp will be pretty warm, not sure if I'm comfortable leaving it running if I'm getting these temps in an AC'd room
Maybe I could manage it remotely and underclock if it gets too hot?
Bear in mind that the mod REDUCES the airflow over the sensors, so temp readings are not that accurate (even without the mod).
What only you can tell for your ambient is how well the machine is running .... e.g are you getting more HW errors with the mod, are you getting higher diffs / faster diff setting by the pool? If you are getting less errors (assuming you've OC'ed), then that is a good sign the mod is doing well.