This advice from Jeff Gaudette "coach" at Runnersconnect.net
"If you’re pacing a friend, the start of a race is too congested to be of much assistance anyway. You’re better served jumping in at 6 miles, when the crowds begin to thin out, and being a little more fresh the last 6 miles to help give the pacing and motivation your running partner needs. (note: I don’t condone banditing races. I always suggest you pay the full race fee no matter how much of the course you will be running). "
So pay to enter the race (admirable) and start 6 miles into it. Looks like something a few of our marathon cheating friends might want to try. And coach Jeff is teaching them its the way to go.