Another Oscar can be a good tank mate, but my research indicates another red/tiger oscar would be the best option for getting along. Taming your Oscar and actually massaging/stroking the back half of it's body can reduce aggressive behavior and make for a calmer fish. I actually saw a video short of it, but the video was not explanatory or helpful in the technique.
To immediately stop a fight, another suggested technique is to quickly cover tank with a blanket and out the tank lights. Probably start by cuping your hand with food in it and using your other hand to stroke starting with a finger or too, unless you have already progressed beyond that. The video short showed the person using their entire hand to lightly stroke the Oscar.
You already know this-- set up a new area with rocks plants and hideout so the fish has it's own area.
Further research again indicates other tank mates same species or others can diffuse aggression. Banded Leporinis, also Convict cichlid were other suggested tank mates for Oscars or other previously mentioned compatible fish. Or as
Deadliestviper7
suggested get Eclipse Catfish other cat to eat left over fish food and Scatphagus that eats fish waste. This would reduce your chores