Well based on today's run, I'd say yesterday's freakout was an overreaction. I ran today around 5:30, 4 out and backs on the main trail by my house. I just started easier than I normally would. I still ended up progressing over the course of the run, and wasn't actually all that slow overall, but it was always at a pace that felt perfectly manageable in the weather. It was still a hot one, but as long as I keep in shade (and preferably shade that's been there all day) and start easier than I feel like I should be starting, I should be able to knock out runs right after work on even hot hot days like this (~90 for the run though cooler in the shade).
Got my pass for the trails on the naval base finally!