That humidity is the killer. In '98 we went to Bonneville, and I never was a heat person. Out on the salt it was 105°F and no shade other than competitors tents. Dry as a popcorn farther in a sand storm.
There is an ice cream truck driving around the pits selling quarts of water. That year being the 50th, there was onrow of pits 1 mile long, one 3/4 mile, and one 1/2 mile. After walking the one mile and looking into the pits, you were thirsty, so a quart of water. Never got wet though as the sweat evaporated as quick as it came out of you.
Before leaving I had cleaned out 4 - 4 liter plastic milk jugs (a little more than a gallon). At night I got ice from the ice machine down the hall and pushed it into the jugs. Kept them in the cooler overnight. Then we had cold water back at the '41 Ford truck all day. Saved on buying water.
Of course the ice machines are MT by 6AM from the competitors heading out earlier.