[Spoilers All] Tips on a "Jerkquisitor" run?

I'm thinking of starting a new DA:I run with a "Jerkquisitor". I'm well aware that you can't really make a lot of "evil" choices like you could in DAO, but I'm interested in trying to do a run where I make all the "wrong" choices and still manage to finish the game (which means I can't mess up too badly at the Winter Palace, I guess).

I'm thinking of an aging male Cadash, a grumpy, jaded old bastard who romances nobody except maybe to flirt with Scout Harding, a relationship that goes nowhere but does get a nod in Trespasser, I believe.

I'm also aware of most of the major choices and which ones I think would be "bad" (but, again, the Inquisitor can be a cynical hardass but not really do a lot of "bad" stuff). I know the game rewards you for mercy (for example, keeping certain people alive rather than killing them gets you rewards via the War Table), so I'm okay with losing those possibilities.

The only "bad" choice I'm dreading is telling Cullen to stay on the lyrium, because I know what will happen to him after Trespasser... ☹️

Anyway, if anyone has done a "Jerkquisitor" run and has any advice or tips on the best (worst?) way to do it, I'd be happy to hear about it. I want to be the biggest jerk possible while still managing to get the job done.