Land use here in VT is a touchy subject with the locals (especially in the ultra liberal town of Stowe) but there are a good number of 'Class IV' unmaintained roads that would test a stock JK. Below is a link that may help you find what you are looking for. Worst case scenario you can always ask someone if they know of any public trails. And while it isn't offroad, I highly suggest a drive through Smugger's Notch (VT 108) between Stowe and Jeffersonville. Perfect weekend to check out the color change.
Vermont - Dirtopia, the Off-Road Encyclopedia
AOT-Mapping: Ancient Roads
If you don't mind the drive from Stowe, there are plenty of Class IV roads in Washington and Addison Counties too.