I had a classmate at LSU back in the '70s who commuted by bike on a gnarly, busy two-lane death road (Highland Rd). Hateful. One day he noticed a broken child carrier on someone's trash heap and got the idea to carry his books etc., in that. (There weren't tons of options for bike racks back then that a college kid could afford). He rigged it up over his rear wheel and guess what? Motorists we're almost going in the ditches in the far lane to pass him thinking he had a kid in there. He was not expecting that! So he added a little ball cap to the top of the kid seat so it was more convincing.

Yes, some motorists do react differently to how cyclists appear to them. When I get old and slow I will try the baby seat trick myself. They don't weigh much and will even carry your lunch!