Why should one parent's wish to have the child the majority of the time take precedence over the other parents wish to also spend a decent amount of time? Disney parenting is inevitable when one parent can only have a couple of days a week/fortnight with a child as no opportunity to establish a normal relaxed routine can be had.
Two over nights and three days is actually not far off from 50% of a five year old's free time, particularly if you just count the hours they are awake.
Speaking from experience, being with a Disney parent for this proportion of their time is not at all helpful to the resident "mundane" parent.
I could have written your post a year or so ago OP, down to the DD5 and amount of time she spends with an ex who when we were together took very little interest in her.
That is why we didn't do 50:50, because when we split, I was by far and away the primary carer. Yes, it's great that the one good thing that came out of our split was he took his head out of his arse and started to focus on his relationship with her, but very nearly to the detriment of mine.
His job demanded flexibility and he exploited this and it was impossible to get into a settled pattern with decent opportunities for quality time with her. My life revolved around his work schedule. And when I came on here to moan about it I was told by some to suck it up because he had every right to an equal relationship with her.
Six months ago, I went to a solicitor and was advised that as we didn't have a court agreeement, I could send him a letter outlining the contact arrangements (as long as I was reasonable) and if he wanted any different, he could take me to court.
He swings from demanding more time with her to dropping his time with her when something more important comes up. Ultimately, he knows that if he did go to court and make things formal, he would have to make changes himself, so he never has.
Things are now much more "professional". I get proper stretches of time now with DD and our relationship has really got so much better.
We are still beholden to Exh's work schedule in some ways though. I would actually love a structured EoW routine, maybe with a Eo week night thrown in and I think DD would benefit from that too. She says herself, she prefers to have longer stretches rather than being bounced back and to.
I would see his change in work pattern as a great opportunity for you and your DD.