Yes Dan is correct. Your meadow park camping pass will cover Monday-Monday.
though Monday thru Thursday is pretty quiet. Many people come and set up tents etc on Monday and then leave and go work til Thursday night when they return for the festival. Personally this is what I will do, though I'll be returning Wednesday night.
As for your hammock question. There are many trees in Meadow Park and technically you likely could sleep in one, but this is Colorado and it still gets somewhat cool at night. Also in case you didn't know there was a flood there a year and a half ago and while they are working on repairing the park it is possible they will not be totally finished and access to the river and/or some of the trees where hammocks usually get set up may not be available.
Either way great decision coming across the pond for our little festival!
I am a Folks Festival/meadow park veteran (This will make yr 7 for me I believe) and my dad lives in Lyons, many other members of my family stay in MP as well and we have a great if not somewhat mellow, time.
Let me know if you have any questions or if you need anything a local can provide. Dan this goes for you too.
Happy Festivating
Nate Grant
Listening to:
Acoustic Cafe