of course you can, and no your aren't crazy. Starting at 6 am will be a big help with the heat. Just take your time, stop when you need to, spin as opposed to hammering on your gears.
Don't depend on the SAG stops for your fuel - take the food you are used to and the electrolyte replacement you are used to. Don't want to have stomach issues on your first big adventure.

Of course, continue to push your miles between now and the 22nd as it will be more about your fitness level than the distance.