First: I’d try to deescalate the situation. Second: I’d make a move towards the exit. When those fail I’d make my mind up to stand my ground. Most intoxicated folks have courage from the drinks and won’t focus on anything but the conquest. You may be able to temporarily refocus his attention but may not keep them long. By making my move towards an exit I could speak to the bartender as I go past them towards the exit setting up the fact I do not want to be involved.
If they manage to block me from leaving, then I have no choice but to engage and stop the threat by any means necessary. They being drunk doesn’t affect the need, as I don’t know them and their strength. The fact he works construction says he may be stronger then I am, so unarmed and at a disadvantage, I do fear for my well being.
Situational awareness, he’s drunk and I am not close to an exit. Verbally i made my intentions well known. Create space, try to exit or get close to door, call attention to my trying to leave. And finding a weapon of opportunity handy when all else fails. And I would exit after it is concluded but not leave from area. Maybe near the doors or move my car closer.