D. your a good guy and poster but your a little off on this topic. The vetical exhaust dramatically lowers the smell of fumes outside the tractor and being vertical does not cause more fumes in the cab. The smell of fumes in the cab is non issue wether vertical or not. Before I had vertical exhaust most work done on the ground by the tractor had fumes. I don't even notice fumes with vertical exhaust.
I trailer my tractor all the time and don't even consider covering the vertical exhaust. Even in rain. Most of these exhaust pipes have a weep hole for rain to leak out. The vertical exhaust can be rotated and postioned in 4 places. A five second task. If wind/rain/debris is still a concern, just rotate the pipe the direction you need.
The only real negatives to vertical exhaust is cost and installation time on a cab tractor. On a noncab tractor, vertical exhaust would be more likely to be damaged by hitting something with it. This could happen with a cab tractor also, but I would rather have my exhaust bent than something hitting the cab. Hitting the vertical exhaust may give me enough time to stop before something hit the cab.