Dann, option B will tear off his wind screen if he goes highway speed with out his cover on.
Matt, my guess is 2-3" per side loss max. My little truck (2004 Ford Explorer Sportrac) has a box too small for anything except groceries so I trailer my sled. I have a nice ramp/gate on my trailer so it makes it alot nicer for loading and unloading. Additionaly my sled is 9' long so it would hang out 4' !