A question: Does GURPS have any rules for slapstick brawls, like those in a Bud Spencer movie? In such fights, the brawlers constantly use their environment for comedic effect, and they only ever fall unconscious if they lose the fight (maybe with the addition of some bruises), with no real lasting injuries.
I am asking because while I like the setting of Brancalonia, I don’t think Dungeons & Dragons is a good fit for it - but default GURPS brawling rules strike me as too lethal.
When all else fails, a few rounds of ‘rolling for shoes’ could give you the basics of the desired system.