There's a thread on ST-Owners about lining the cowl with aluminium foil. It's a lot of work, but had some benefit. Another suggested fix is removing the centre (black) cowl in front of the radiator to improve airflow. Another has holes drilled in the inner cowl also for better airflow.
So it's not uncommon, but oddly, not universal.
I bought exhaust pipe bandage to try to keep the heat from coming off the pipes but a mechanic advised against it, saying it would concentrate the heat on the heads with ill effects.
So jeans and highway pegs rule. Not ideal, but manageable. Let's face it- hot days are miserable in the jackets and helmets. Maybe leave the bike in the shed when it's over 25o out if you own a hot one?