@Tuco Salamanca
You got me curious, so I went to look at records in the Big Ten broken down by division and crossover. Here is how the top three in each division has shaken out since the league split into two divisions.
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Year: Division
Rank. Team: Conference Record (Division Record, Crossover Record)
2018: East
1. Ohio State: 8-1 (6-0, 2-1)
2. Michigan: 8-1 (5-1, 3-0)
3. Penn State: 6-3 (3-3, 3-0)
2018: West
1. Northwestern: 8-1 (6-0, 2-1)
2. Wisconsin: 5-4 (3-3, 2-1)
3. Purdue: 5-4 (3-3, 2-1)
2017: East
1. Ohio State: 8-1 (6-0, 2-1)
2. Michigan State: 7-2 (5-1, 2-1)
3. Penn State: 7-2 (4-2, 3-0)
2017: West
1. Wisconsin: 9-0 (6-0, 3-0)
2. Northwestern: 7-2 (5-1, 2-1)
3. Iowa: 4-5 (3-3, 1-2)
2016: East
1. Penn State: 8-1 (5-1, 3-0)
2. Ohio State: 8-1 (5-1, 3-0)
3. Michigan: 7-2 (5-1, 2-1)
2016: West
1. Wisconsin: 7-2 (6-0, 1-2)
2. Iowa: 6-3 (4-2, 2-1)
3. Nebraska: 6-3 (4-2, 2-1)
2015: East
1. Michigan State: 7-1 (6-0, 1-1)
2. Ohio State: 7-1 (5-1, 2-0)
3. Michigan: 6-2 (4-2, 2-0)
2015: West
1. Iowa: 8-0 (6-0, 2-0)
2. Northwestern: 6-2 (5-1, 1-1)
3. Wisconsin: 6-2 (4-2, 2-0)
2014: East
1. Ohio State: 8-0 (6-0, 2-0)
2. Michigan State: 7-1 (5-1, 2-0)
3. Maryland: 4-4 (3-3, 1-1)
2014: West
1. Wisconsin: 7-1 (5-1, 2-0)
2. Minnesota: 5-3 (4-2, 1-1)
3. Nebraska: 5-3 (4-2, 1-1)
2013: Legends
1. Michigan State: 8-0 (6-0, 2-0)
2. Iowa: 5-3 (5-1, 0-2)
3. Nebraska: 5-3 (3-3, 2-0)
2013: Leaders
1. Ohio State: 8-0 (6-0, 2-0)
2. Wisconsin: 6-2 (4-2, 2-0)
3. Penn State: 4-4 (4-2, 0-2)
2012: Legends
1. Nebraska: 7-1 (6-0, 1-1)
2. Michigan: 6-2 (5-1, 1-1)
3. Northwestern: 5-3 (4-2, 1-1)
2012: Leaders
1. Ohio State: 8-0 (6-0, 2-0)
2. Penn State: 6-2 (4-2, 2-0)
3. Wisconsin: 4-4 (4-2, 0-2)
2011: Legends
1. Michigan State: 7-1 (5-1, 2-0)
2. Michigan: 6-2 (4-2, 2-0)
3. Nebraska: 5-3 (4-2, 1-1)
2011: Leaders
1. Wisconsin: 6-2 (5-1, 1-1)
2. Penn State: 6-2 (5-1, 1-1)
3. Purdue: 4-4 (4-2, 0-2)
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To your point, at worst, the division champion has been determined by head-to-head (strange probation circumstances for Ohio State and Penn State in 2012 notwithstanding). The only situation where I found a sliver of a chance a crossover had an impact on determining a division champion was the 2016 East Division:
Penn State, Ohio State, and Michigan went 1-1 against each other.
Penn State (Minnesota, Purdue, Iowa in crossovers) and Ohio State (Wisconsin, Northwestern, Nebraska) went 3-0 in crossovers, while Michigan went 2-1 (beat Wisconsin and Illinois, lost to Iowa).
Not sure how the tiebreaker would have shaken out had Michigan beat Iowa. I think it would have been the CFP standings or something, and given the CFP rankings heading into Thanksgiving weekend, Ohio State's win over Michigan would have made Ohio State the representative.
Wish I had time to check out the SEC, but was curious to see if by raw results there was ever a case where crossover assignments impacted the division champion in at least the Big Ten. The answer is that it hasn't as you've said in this thread.
