are you sure you are buying aisle seats? i can't imagine sitting at window being 196cm, but in aisle i can stretch at least one leg (though i got used to being occasionally hit by flight attendants) and the other one must go to space between seats in front of me since i can't sit straight, it's physically impossible

i would propose except paying for seat apparently paying for weight, your already have to pay for heavier baggage anyway, why not pay more for weight, you can at least influence that unlike height