I am going to admit something and please don't pass judgement!
I turned the car seat around when Caden was only 7.5 kilos. It was just a trial, as he too screamed in the car constantly no matter what I did (music, toys, mirror, etc). I find that if I am turned around in my seat to play with him I get terribly car sick, so maybe that affected him also?

My justification was that driving with a screaming baby was enough to CAUSE and accident, even though rear-facing was safer IN an accident. DH drives like a bat out of hell if Caden is driving and I worry about this causing accidents also.

So I turned it around as a one-of trial, thinking if it didn't work I could always turn it back around and at least he is a safer screaming baby.

Well, it worked like a switch! Now he is so content and often falls asleep in the car where nothing else works. Mind you, now he is over 9 kilos so weight is no longer an issue. He is in the middle so he can see us and the front windscreen, and is so much happier.

Your choice though, maybe just wait until he is old enough to turn.