Not much a person can do other then cooling the bondo in a refridgerator ( DO NOT FREEZE ) to help cool it down for a little longer application .
That will help the bondo from being the same temp as the out side 120* as each 10 * increase speeds up dry time .
Using less of the hardner will help , and by adding some bondo honey , that will help with the spreading smoothness.
Hope this will help
Spray