With cartel on scraptrap and his minions will fight the cartel members taking the heat off you and allowing you to stand far enough back to allow the yellowcake to split and do full damage.
I have found a reflux does excellent damage to him and will clear out the room with just a few shots. (it also takes down fish slap really well). Or quick stack an anarchy.
Sandhawk works pretty well for me. I have, just for giggles, done the whole scraptrap encounter using nothing but a sandhawk. Of course that was with a fade away flak build so I was regenerating ammo like crazy on those crits.
Cartel definately adds a ton of experience and loot to the fight. Went from Guardian 280 to 300 to cap them off on Scraptrap farm. Two and a half runs would give one rank.
Don’t forget, it is bugged right now so that if you enter FFYL the exp modifier drops to zero so no reason to finish the fight. As soon as you go FFYL just stand then quit reset it or use the ledge trick to reset.
Sorry, post kind of rambled but, hope some of this helps out.