Although I ran a sub-8:00 mile in a short course Thursday night, I tend to try for a 9:00 pace for 5K distance and 10:30 for 10K+, because I have to manage my asthma during times (like today, unfortunately) where I either forget my inhaler or the heat/humidity can be overwhelming.
What you said about pre-race prep is mostly true, except it's better to use electrolyte tabs/formulated chews or drinks instead of only water, as water alone after an hour can dilute electrolytes and create a condition akin to intoxication.
It was so hot that I walked at least 1/3 of the time after Mile 6 and still finished 2:47:50, but considering even the 5x marathon course winner had his slowest time by 15 minutes today, I'll take this as a building block for next year's marathon. But until then, I think I'll switch back to running trails more often, as I seem to be built more for that style of running compared to road courses.
Je suis méchant.