Welcome to the Chicago area! You will be SHOT for off-roading anywhere around here. Also, you are moving to the 'burbs, not Chicago, prepare to be bombed by Beezil.
That said...you will find the occasional play area, watch for quads, and bikes to find them. Any spots you find will be illegal, so keep that in mind and wiegh your risks. As far as clubs..there are a few, Mudslingers, GLJT, but this is the BEST club for XJ owners, trust me here. If you need a friend when you get here, shoot me a PM and we can kill some brain cells.
Rev