How to Beat on the Brat?

I’m struggling with a few of the Beat on the Brat quests. I tried looking up some ways and perks to improve combat with fists, but I couldn’t find much for 1v1 situations, mostly the perks deal with using your fists in regular game combat (utilizing cold blood stacks, 1 vs many enemies, etc).

The twins fight was relatively easy, and I’m sure it was supposed to be. However, fighting the army guy and the guy with the pregnant girlfriend was no easy task. It mostly involved me sprinting away from their hits, and going in for some heavy punches, just before running out of stamina so I could still move quickly.

These guys would still knock me out in about 3 or 4 hits, so I’d have to be extremely careful. Playing this way would take around 5+ minutes per fight, and if I made a mistake with them having 10% or less health, it would lead to a frustrating loss and a quick load. I’m not even going to get started on the Animals champion, since Rhino absolutely bodies me with this strategy.

IIRC using Gorilla Arms is not allowed for these fights, but I’m not confident on that. So, how can I Beat on the Brat?