interesting idea,but you will leave yourself open to abuse, mostly from the sub species, and their offshoots...the balloon chasers.
i can see people setting up the barfine, eating/drinking the 200bt away and leaving alone, it wouldnt be hard to say to a girl, go in there sit down and drink for free, and when i come in come sit with me.
Boom the girl drinks for free, i get a free meal or a few free drinks and then i decide not to take the girl and off i go, fed and watered.
nice idea but really open for abuse.