[potato3732842]

>A lot could probably be done with a simple "a person 1.80m in length must be able to see a 50cm high object 1 metre in front of the car" or something like that. Just making up numbers here and don't know what would be reasonable, but it seems this doesn't need to be that hard?

It's hard because the people pushing for new rules very transparently want rules far beyond what the public wants or considers sensible. If they were simply asking for that it'd probable be done already.