OP, as you undoubtedly will be doing the majority of care and mental load, be wary of asking the bare minimum.
Life can throw the unexpected at you and how would you manage?
You need a buffer banked.
As children age, particularly into the mid late teens, they are vulnerable to financial manipulation by a better off parent.
They are only human and high flying dad who will fund anything can be seductive.
I'm not suggesting you go up against in that, but just that the disparity isn't stark.
Get a buffer. You need and deserve one.
Don't fall for the mistaken higher ground that leaves you struggling.
Doing it for the quiet life now would be a huge mistake.
If your solicitor is great, be guided by them to get you a good deal.
You have easily 15+ years of supporting your children.
A vain vacuous man like your Ex is so vulnerable to a new woman in his ear telling him to play hard ball.
My neighbours daughter was so reasonable with her well paid Ex husband after 20 years of marriage. He assured her that he would be her backup.
A mere 18 months later, re married and expecting another child with a much younger woman, he now has zero extra for his older children.
She wouldn't be told, was focused on the high moral ground.
Her pissed off elderly parents are now helping out in their 80's.
Financially prepare for the worst and hope for the best.
You are doing great, but a lonely man, who has messed up his life, is very vulnerable to falling for the first woman that gives him attention.
Half the time these idiots in their late 40's bitterly regret their second families.
I definitely know of several.