Thanks to all for the assistance.
I don't have the route for this year's OHR but I did find the route for 2006 on MapMyRide. I'm sure it is nearly the same. It looks do-able.
I guess I'll be getting intimate with the Pungo Ferry Bridge. I'll have to park the road bike & begin training on the MTB. I'll lower the air pressure and strap some sandbags to the frame. I thought my big butt would be enough training weight. Dragging a tire is a good idea -- should i use a 650 or 700??
Seriously, I appreciate all the input and will use the training tips/tricks to varing degrees.