Steele,
I must agree with the others about the roof rack.
With my old road bike I wasn't as concerned about using my bike as a rear bumper. But when I bought my
Litespeed :thumbup:
and was driving it home for the first time, I'd cringe every time a car pulled up behind me. I bought a Yakima roof rack the next day and have had no problems whatsoever.
If you value your bike(s), pay the extra money for a roof rack. And since I can lock it, I'm not worried if I must leave it unattended for a short time.
Look on the posting board at your LBS to see if there is one for sale. Or try the newspaper, ask members of a local cycling club, etc.
Good luck and have a safe trip. Be sure to tell us about it when you get home.
Ron