Way too easy to break a hand. Way too easy to get knocked out by a lucky punch. Plus, even if you KO the guy he could hit his head on concrete and fucking die. Now you just killed somebody, good luck in court.
In a one on one fight you should control the distance, clinch, throw elbows, knees. Maybe go for a takedown. Obtain a dominant position and pound him out. Watch out for his friends that could jump in.
Really the best thing to do is swallow your pride and fuck off. Don't fight any optional fights. Fist fighting in 2017 is fucking stupid.
Takedown in a streetfight is rarely a good idea. Unless you roll everyday or at least a couple times a week, the odds of you landing in a dominant position isn't great. Not to mention ground n pounding a guy and slamming your fist, even a hammer fist, into the concrete is no bueno... Nevermind you dont have eyes in the back or sides of your head and have no idea whosjudona soccer kick your skull.
Best bet is throwing short strikes (hooks to the chin and jaw for example, maybe temple... Hit the skull and your hand goes pop)... Clinch up and throw elbows if you know how. Learn some basic judo and throw him to the ground and always stay on your feet. Him on the grOund and you standing over him is always THE most dominant position.
And as a bouncer, your first (2nd and 3rd) response is always verbal de-escalation... Then physical restraint/neutralize the threat. Throwing a strike is always a last resort. Bouncers who fight wont have a job long as club owners (as well as co-workers and every "bouncer" on payroll that night) dont care much for showing up to court at 8am on a tuesday to explain the events and how the knumbskull felt his use of force was justifiable and necessary..