I wouldn't want to but...
I would allow it. Supervising parent is there, other kids will be, yours will probably do it without your knowledge and out of control if you try to make it forbidden.
I was the only one of my friends growing up who didn't have a curfew and whose mother said, just be very careful, don't mix drinks, remember you don't need to drink the bar dry, always have money separate for a cab home and leave if you start to feel unwell.
I was also the only one of my friends who was always home early and I rarely drank, now I never do.
Forbidden fruit and making a teenager hate you, unfortunately that backfires.
Yes definitely the open discussion about different types of alcohol, the effects, what is wrong effect and have to go home, spacing them out (soft drink of water in between is a good tip for everyone), call you if there is a problem and there will be no judgement from you, stupid things people do when drunk, things to never do when drinking and that you don't have to drink just because others are!
Maximum is a good idea, although three in six hours, as a non drinker I'd be sloshed:)