OP, you are right that divorce is crap for the kids (I am divorced).
I'm a bit shocked that 50:50 seems to be becoming normalised. It wasn't when I divorced, 6 years ago. Then, residence was based on maintaining the children's status quo as far as possible. So if they had had a SAHP, then that parent would automatically have them for a greater proportion of the time, unless there was a very compelling reason for them not to. I think this is a better yardstick. A (male) friend of mine actually tried to get 50:50 about 15 years ago (he worked ft, and his wife worked pt - both medics). He ended up with one night per week and EOW. In practice, this has worked ok for everyone.
My DC were teenagers at the time, so it was irrelevant. I did, however, make sure I lived close to their father so they could come and go easily, depending on how they felt. I have always been the 'base', though.
Has your colleague thought about exploring the option of the children staying in the family home (or a smaller family home, if the main home has to be sold), and the parents taking it in turns to be at home with them? I know someone who does this. It's a bit crap for the parent who has to stay elsewhere (the mum has rented a tiny flat, and the dad has a girlfriend to stay with), but it's less disruptive for their children - and it seems better for the parents to take the hit of having to do the to-ing and fro-ing, rather than the children. The resident parent then obviously has to shoulder all the day-to-day parenting, homework, PE kit, permission slips, etc, etc. I know it might be ruled out financially, though.