If you're willing to drive to Indiana, Summit Lake State Park has an idle zone lake, and very seldom anyone with motors are actually on it, unless they are fishing with battery operated motors.
We really love Summit Lake because we have a canoe and it's so calm and peaceful.
Also, Potato Creek State Park in Indiana (Near South Bend) in the Northern part of Indiana has a REALLY nice idle zone lake also that's perfect for paddle boats. This is our second most favorite spot.
(If you're willing to go this far).