Susan, very respectable time on your unofficial half marathon.
I used to always finish a race in about that time. (worked w/ a coachto get down to 2:10) Believe it or not that really puts in the middle of the pack. You'll probably cut off some time w/ the whole race excitment/adreneline rush.
And to do that alone at 4:30 in the AM...you go girl! Long run in the middle of the week? WOW!