Your co-channel problem reminds me of what balm
is trying to do to get reliable reception of WVNY with a co-channel local signal off the back of his antenna:
The tvfool report that he posted for St-Anicet looks like this:
WVNY is very weak for him at his summer cottage and his requirements are:
1. High gain antenna for CH13
2. Ground the coax of the antenna system and TV to shield them from a strong local analog signal (helpful suggestion from holl_ands because the strong local couldn't be eliminated even with 50dB of attenuation!)
3. Mount antenna at optimum height to max signal enhancement from ground reflection ("ground bounce"). His tvfool report was correct about the best height
4. Design antenna for max F to B ratio
5. Utilize any helpful reflections in front of the antenna without picking up any reflections from the undesired co-channel signal from the rear
Balm tried stagger stacking, but it didn't give enough F to B to eliminate the undesired co-channel signal.
He built a nice long yagi for CH13 but it still wasn't enough.
When he aimed his antenna at his metal boathouse that was slightly off-azimuth for WVNY, it gave some signal enhancement, but it probably also reflected some signal from the undesired co-channel signal from the rear.
He plans to try again this spring, and is considering a VHF 4-bay CH12 antenna in an enclosure shielded at the rear and all 4 sides...a monster antenna. The trick will be to keep it from picking up any reflections from the rear signal without sacrificing any signal enhancement from the front.
He made some tests in the fall by mounting his antenna inside the boathouse to eliminate any signals from the rear and sides. WVNY was very weak, which leads me to believe that the tvfool report was too optimisitic.
Even if you mount your antenna in a well shielded enclosure for the sides and back, you still must be careful not to pick-up any reflections in front of the antenna that come from the undesired co-channel signal.
One serious problem that you have is that WISC is 85 miles away. The curvature of the earth starts to become a problem at about 70 miles:
This is the WVNY profile for Balm: