I would go for it though I would probably 'ration' the alcohol and not have the hard stuff on hand until afterwards. For those I work with who are of legal drinking age nd that's the vast majority, I routinely have wine or beer available for those who wish it. I don't usually drink during shoots, or at least very little, but it's there for those who want it. Sometimes it even helps!  Drinking is not really an either/or situation, a glass of wine doesn't usually mean someone is drunk. 

But then ...

Don't click this if you are timid!

http://www.distinctiveimages.com/temp/mic065.jpg

Drunk AND naked on a beautiful day with music and fun ...

I'd be willing to pay a cover charge for that one.