No pain no gain LOL!! Here is what we do when we have paint correction jobs and we know it is going to get hot.
1- start early, We will try to be there at the butt crack of dawn if at all possible. It will be nice and cool and give you a good 4 to 6 hours before the heat cranks on you.
2- move the vehicle in-doors. Garage, shop, warehouse......anything
3- take your breaks, drink plenty of water. I'll go sit in my van for 5 min. with the A/C and cool down a bit.
4- if all else fails, don't do it. Paint is tough to correct hot. When paint gets hot it gets soft.
You will not do a good job if your hot and uncomfortable.
See the b-17 in my avatar? We did that in the sun. It was April and in the high 70s low 80s but still the heat wore on us. We started on the top side early then moved to under the craft in the afternoon.