Summer to Winter switch is September 15 in Idaho, according to the Google Man. Could be dated info, or different if you’re in an ozone non-attainment area.
Also, if the problem is engine-off heat soak, not sure the return fuel line will help. Opening the hood would solve the problem, but might not always be practical.
I have two vehicles with different fuel/temp issues with winter gas on hot days. One is vapor lock, the other is fuel boiling in the carb while driving. Knowing the specific condition and cause Ihave been able to easily work around the conditions.