I parked at the Byron Reece trailhead over Christmas when I did my day hike of Blood Mountain. It was pretty straight up and down; a ~4.8 mile hike took me about two and and half hours, pushing pretty hard. So, be prepared for the last two or three miles of Wednesday to be pretty straight down.
I think parking one of the cars there, if feasible, would probably be our best bet. That way, we don't have to worry about timing a shuttle.