How big are some of the auto haulers....

If you know what you're doing, door openings aren't an issue on a highrail.

There's a guy running a high-mount I see every day that's got to pushing the 400# mark. Loads pretty dang fast, but he doesn't load anything bigger than a minivan.

 

Used to see a lot of windows down on auction cars in the 6 & 7 spot of a high mount going down the road.

 

I'm 6'5" and 270. I have a hard time in certain spots with tiny cars...but you adapt. I imagine they have to plan their loads a little better but it's definitely doable.

 

Ehh, I;m 6'2" and right at a svelte 290, my weight is much less of an issue than my knees.

 

Back in the early 80's I knew a guy that was leased on to Arco Auto Carriers, the import division of NuCar Carriers. He was every bit of 375 if not more. Hauled imports out of Port Newark and that was with a 96" wide trailer. He was a hell of a carhauler.