There are solutions to most, if not all of the companions.
Lae'Zel? Just side with the Tieflings and kill her. Then you get to loot her corpse.
Gale at least gives you a means of initiating combat with him in the introductory dialogue... though looting his corpse can be a bit more complicated.
Astarion and Shadowheart both have the ability to be attacked from outside of their dialogue trigger zone.
Wyll, just takes a wee bit of patience and you can let the Goblins kill him before he ever becomes an issue.
