We ordered tickets for the family a few months ago and will be going next month. Not sure if there is any difficulty in getting tickets now.
My daughter is pretty pumped about it... we studied Ancient Egypt a couple years ago. She wanted to visit the Valley of the Kings at the time....this will have to suffice.
We have a site reserved at Indiana Dunes State Park for the trip. Our first stay at the Dunes was last year in September...it was a nice and quiet time to visit. Just a short distance from the park entrance there is a station for the commuter train line into the city. We plan to use it to get into the city for the Tutankhamun exhibit. That might be further out than you want to be. The timetable I have from last year shows it is about an hour ride. Our entry time at the Museum is 11:00 am so not an excessively busy time to ride the train. We might only use it one day and take our truck into the city the other days.
Another very nice campsite on the extreme northwest side of the city is Paul Wolff Campground, a Kane county park with camping (electric only). Worked nicely for us when we went to a conference in Hoffman Estates earlier this year. Quite a distance from the Field Museum though.
Thanks for reminding me I have to get an updated timetable.