[750hp]

Trev if you're at all on the tall side you'll have to experiment a bit.
Don't try to slide forward and down to get your head out of the windflow, that only reduces the amount of support for your lumbar back.
Push your bum back and sit up tall. (This is also a well known practice to maintain alertness while driving, so you're doing two good things, staying alert and being kind to your lower back.)

You'll have to jam your cap on tighter but.....that's part of the price you have to pay. You're not in a luxo barge now.
Then buy an el cheapo KMart cushion and place it behind the lumbar area of your lower back, not your bum. You might have to modify it until it feels comfortable and when that happy day arrives, cover it to suit your upholstery and velcro it in place. Done! Doesn't matter what it looks like, it has to be supportive for you. You might consider buying an offcut from an upholstery shop if you need firmer rubber, and cut it to the same size and shape.

There's an old biker's saying "You're not in the carriage now, you're up on the horse!" Same goes for Cobras although not to the same extent. They'll never be super comfortable, they're loud, they're not politically correct, greenies hate "em, they're a throwback to better happier times.........and that's why we love them!!!