A question and an observation...
How does the chute on the snowblower get turned? I'm gonna take a guess and say the main PTO powers the blower and the AUX PTO knee lever powers the chute rotation direction, but just want to confirm.
I think your idea about using fabric to enclose the bottom is about the only way to go. There is a ton of flex in the unit when it articulates AND oscillates. I have the factory arm rests and they will rub the engine cover when I am in full articulation and oscillation.
You are correct MR, the AUX knee lever turns the chute. Since there are no stops on the chute, it does go around a complete 360, so you have to be careful or you can send it right back in your face. I have come close, but that is another good reason for the cab!