Yeah I don't think it's possible to get everyone's disapproval scene. Like it's easy to get everyone's approval scene, because you can make back any losses, but there very few ways you can "farm" for disapproval, and anytime you get someone to Greatly Disapprove, you've gotten someone else to Greatly Approve, and it's a difficult balance to strike.
What you could probably easily do is get Blackwall, Cole, and Dorian to leave? I think they're the only ones who will leave. And kick out Sera. I'm not sure. TBH, this character was mostly conceived around "punch then romance solas" not "be the most evil" so I mostly investigated 1) how to ****** off Solas 2) how to get approval back from Solas 3) if I needed to keep his approval up to keep the relationship going. Then I realized I could dump other people as I went. Then I realized a character with a string of bad relationships and tendency towards violence when frustrated would probably not be the best leader, so how could I make her have terrible decisions? Which all came after Skyhold, and honestly I think in order to game everyone's disapproval, you'd have to micromanage from the beginning, and I only did it with Solas.
Honestly the decisions in the game that squick me out the most are either not available to my character (like making people tranquil, because she's a rogue) or aren't really framed as bad decisions (like reuniting celene and briala) so it's not really capable of supporting an "evil" run like DA:O or DA2 does imo, just more of a "selfish and socially inept hypocrite ruthless trainwreck".