I've done a recreational 200 km ride at about 48C (in Winnipeg area). And the first 400 kms of a 1200K (in California) in about the same type of heat. I was fine on those occasions, although I think I did start to feel it on the 400K. However, I DNF'd a century (first one of over 100 centuries I've ever DNF'd!) due to heat related issues when the temps were about 40C this past year (in central Alberta). I'm not as used to the heat as I used to be.

And people should eat 5 smaller meals a day anyway, no matter what the temperature.

Planning a ride across the Sahara??