Tha article is about banning the conversion of street vehicles to race only - hence to control or limits on emission controls. It has no implications, as written, for street vehicles that are already regulated for emissions. This has nothing to do with safety. The EPA doesn't regulate that. They regulate the emissions and that is what they are doing here. You can still have a street car, subject to regular emission standards, and modify within those rules.
I haven't tried it in clear plastic. Judging by the perfor ance on regular plastic, if your window glass fit well, I think it would hold. If you had to clamp or tape your glass in and the joint would be under pressure, I don't know. Maybe, maybe not. It does help if you rough up the surface, but that might not be easy on clear parts. Bondic does work for quick filling of holes etc - just fill, light, repeat.
Try the smaller can of Duplicolor. It's light gray, thin, smooth, and doesn't seem to be as hot as the big dark gray can. I used to use he dark gray a lot, now I've switched to the slightly more expensive small can like this: