I'd suggest that anybody who can authorise you to operate outside the aircraft limitations will have the all the answers, and more. Also, please, tell us all where you can get a "Get out of Jail Free Card". But, IMHO, the limitations are there because the manufacturer didn't pay for the certification of aircraft to operate at extremely high temperates, only because they thought nobody would operate in them. If no answers are forthcoming, try drawing out a few graphs, extrapolating outside (like what we are NOT meant to do) the performance data you actually do have and see if that gives you a few clues.