Here's how you and your friends can free pour all the wine you can drink and not have to worry about seeing if the pregnant one in your group will volunteer to be the designated driver. Harvest Hosts is a service aimed at RV owners and they have deals with hundreds of wineries all over the US and Canada that will allow you to camp out at the vineyards. Just sign up for one of their $49 yearly memberships and you can stay overnight for free.
The only catch (there's always a catch) is bathroom facilities are limited to operating hours, but then again, that's why you're staying in a RV. Would you sleep in a vineyard? Does this seem like a cool idea until it gets dark outside? Where's the coolest place you've gone camping?