Your post has successfully reawakened my wanderlust within!
While normally I try to pick good class II-III runs for fun, I also love to explore. It's been a few years since I did the Hogeye run (a short but very fun class II+ in your backyard if you live in Fayetteville). After the trip, my inner explorer and curiosity started saying "Hey Tony, why are you stopping at the pullout spot they told you about? The river goes on, and it was a lot of fun so far."
I'm also heavily addicted to Google Earth (literally it can consume hours with "virtual exploration"). I searched for extended pullout spots for the Hogeye run, and found many. And your post got me going, and I found a few more today. Of course these are personally untested so far, but perhaps a few others also infected with the wanderlust virus can join me for an Upper Illinois Exploration Expedition over the next few months.
Heres a list of access points I've found (and you can download my Google Earth placemarks too if so inclined):
Upper Illinois
Muddy Fork Branch (Put-In Only)
Goose Creek Rd. Access
Wash. Co. Rd 62 Access (as Cal described)
Wash. Co. Rd 623 Access near HWY 62
HWY 62 near Prarie Grove (Questionable access, much traffic)
Wash. Co. Rd 20 (My first imagined Hogeye Run extended pullout spot)
CR 67 (Actual finish for the Hogeye Run)
Hogeye Rd. (Put in for Hogeye Run)
[The extension rar has been deactivated and can no longer be displayed.]
I've only done the Hogeye Run, so take all this as "float at your own risk", as I've had Hogeye locals talk about barbed wire stretching across the river that will "take your head off" upriver of Hogeye Rd. The Hogeye Run usually doesn't "run" unless there's 2.5" or more of rain. Maybe the stuff below it might with less.
Hey, hopefully a few of you can kidnap me from the UofA library (grad student here) so we can do an Upper Illinois Exploration Expedition sometime in the next few months. I'm sometimes free Mondays, Thursdays, and Fridays, but usually have to work most weekends (but not all). Lets do this.
Keep exploring,
Tony