Have you done any easy running on the roads? You were comparing a race
on the roads (which hurt) with (presumably much easier) training runs
on the treadmill. It sure looks like your case argues for doing some
road training before jumping into a road race.
Good suggestions. One thing I forgot to mention in the original post was
that my "race" was really just to be there, I actually did more of a jog.
But I think your advise is sound and will try to incorporate some light
jogs on the road into my schedule.