Hauling a Quad

I am going to purchase my buddies Yamaha 600 4X4 quad. He lives 8 hours away and I dont have a trailer therefore need to use the Avalanche. I want to hear from anyone who has haul a quad or could not fit a quad in the back of their Avalanche.

The quad is 46" wide. Box of Avalanche is plenty wide except at the top where the rails are. Are these difficult to remove? And put back on?

Is there an alternate cover for the Avalanche? A soft cover? That I can use instead of the hard cover? I do not want to be taking these rails off and on every time to haul the quad in the future.

And no, I can not get a trailer. No place to put it.

Thanks for any of your personal experiences with my situation.