I flew an ultralight back in the early '80s. I had several flame outs with my two cycle twin cylinder motor.
It was an axial fan cooled motor and the rear cylinder over heated because of the hot air from the front cylinder. They came out with a modified head that only had half the fins for the front head and that allowed more air and cooler air to make it back to the rear cylinder.
I also changed out to Amsoil and ran at 100:1 ratio for oil/gas. After the head mod and dual head gaskets for cylinder AND the Amsoil, I didn't have any further issues.
I had to land on a road and once in a corn field that had been cut, but the cut cornstalk stubble was still about a foot tall. The problem was that the seat was about 8" from the ground and that was the butt of it, so to speak.
I had pontoons for mine as well and flew off water a lot. In the winter I had snow skis attached. It was great fun and really not too dangerous, in my opinion.
That was a great video of them landing on the road.
I think after the first seizure of the motor, on restart I would have landed it under power rather than attempting to fly on. There were several fields available and landing on the road could have been a killer, especially not know what the power line status was over the road they landed on.