Get out while you can

If you are in Illinois be extremely careful about stopping any physical access to your home. Starting in 2013, under the law, the police can't remove a trespasser unless they are acting threatening.

So basically, if your yard is open access and a few dozen homeless people set-up camp - they stay until you get a Court order. That Court order could take months.

Your 19 year old, decides to have a party a party, there is no way you can have the police chase people home.

Find someone on Craigslist to do a few repairs in your home. If they decide to live in your home for a few weeks, you can't do anything about it.

From what I read; they have to break into your home to be removed. If you invite them in for any reason or if they entered without breaking a lock or property, then they stay until a Court order.