Repair cracked plastic
Sheet aluminum and pop rivets. Extra points for using old beer cans as the aluminum source, label side out, but flashing is a bit thicker than today's beer cans.

Hairy (loaded with fiber reinforcement) Bondo. "Bondo Hair" is the actual label on the can. Some screws or pop-rivets might still be needed to help the bond to the plastic at the edges. Looks awful, but quite sturdy.

Run with no hood at all. It doesn't really serve a functional purpose. And then you can start taking parts to a chrome shop and have a real hot-rod lawn tractor eventually.