Sounds like a great time! You should look up some of the festival guides, and try to go to a few on your trip across country. I'm assuming USA?

We stopped one day at a campground in New Brunswick, Canada, and my husband and I took out a banjo and guitar and started singing and playing. Within 5 seconds, some guy literally came running with his guitar. Spent the rest of the evening having a fine jam.

Another time in Pennsylvania, we played awhile and then some missionary guy rounded us up to join a gospel session in the barn.

Just start playing, and you'll attract lots of listeners and maybe a few pickers. (But be careful about quiet hours and playing too late near your neighbors, something you usually don't have to worry about at a festival).