i need to get this on the roof of our Nissian Quest., I have two requirements:

1: dont damage the van

2: make sure the bike is still on the roof when I arrive after a 4 hr highway drive

i dont really want to buy a bike rack like Thule or similar as this will most likely be the only time I have to do this. I have the standard cross members that came with the van. I was thinking of putting a couple 2X4's front to back and tieing them down and the bike to that. I’m afraid the pedal will scrape the roof if I dont do that.

Any ideas?