Riding to SD

In just a month, I will be riding in W.R.A.T.H., the MS150 ride in Rapid City, SD. I have my hotel reservations and have been training all summer. But I recently discovered that what they call "hills," this flatlander might call a mountain. There are three routes to choose from on Saturday - 27, 67, 99 miles. For the past several years, I have been doing the century ride on Saturday. But this particular route has a climb of 8605' at about mile 80. That just isn't very nice. The 67 mile route climbs only 6575', peaking at about mile 46. I am thinking I will take the shorter of the two. The return trip on Sunday (75 miles) only climbs to 6302'.

Where can I find some hills to train on in Champaign County?