Played around with the options, but I came up with this for a slightly different 3 protected rivalry option, that has a good amount of geographic, historic rivalry, and SOS logic behind it:
Illinois - 1. Northwestern 2. Purdue 3. Nebraska
Indiana - 1. Purdue 2. Michigan State 3. Maryland
Iowa - 1. Wisconsin 2. Minnesota 3. Nebraska
Maryland - 1. Rutgers 2. Penn State 3. Indiana
Michigan - 1. Ohio State 2. Michigan State 3. Rutgers
Michigan State - 1. Michigan 2. Penn State 3. Indiana
Minnesota - 1. Wisconsin 2. Iowa 3. Nebraska
Nebraska - 1. Iowa 2. Minnesota 3. Illinois
Northwestern - 1. Illinois 2. Wisconsin 3. Purdue
Ohio State - 1. Michigan 2. Penn State 3. Rutgers
Penn State - 1. Ohio State 2. Michigan State 3. Maryland
Purdue - 1. Indiana 2. Illinois 3. Northwestern
Rutgers - 1. Maryland 2. Ohio State 3. Rutgers
Wisconsin - 1. Minnesota 2. Iowa 3. Northwestern
This arrangement keeps the Upper Midwest together, has excellent SOS balance between the four powers in the east, sends Michigan and OSU to the "New York market", and brings the schools with the largest alumni base in the Chicagoland area to play Northwestern. While Wisconsin-Northwestern isn't really a historic rivalry, the regional proximity / fan overlap and recent divisional games between the two make it a good match for now. Illinois-Nebraska might feel strange to some, but its actually been a fairly competitive game in recent years. As an alternative they could match Nebraska with Wisconsin or OSU, but Nebraska has only beaten them once each, and hasn't since 2011 & 2012. So I bet they'd consider matching us with them to make things a bit more balanced. The only rivalry that doesn't make sense is Indiana-Maryland, but this is what you get when you add schools like Maryland and Rutgers to the conference.
If I had to rank our likely protected rivalries:
Certain
1. Northwestern
Very Likely
2. Purdue
One of these
3. Indiana (I imagine they prefer to tie IU to a school on the East Coast)
4. OSU (Illibuck; They may want to make us OSU's "easy" rivalry after UM and PSU)
5. Nebraska (Like I discussed before, its been a good game and they may want to "throw Nebraska a bone")
6. Maryland / Rutgers (Maybe we get stuck with a dumb rivalry with the red-headed step-children)
Very small chance
7. Wisconsin (I'd be shocked if Wisconsin's third rival isn't Nebraska or Northwestern. If it isn't I'd next expect someone like MSU)
8. Minnesota (We could get paired with them if they pair Nebraska-Wisconsin instead of Nebraska-Minnesota)
9. Michigan State (I guess they could pair with us instead of Indiana or Purdue)
Guaranteed not to happen
10. Iowa (I know it makes sense from our perspective, but Iowa has to be locked in with all of Wisconsin, Minnesota, and Nebraska)
11. Michigan / Penn State (They will be paired up with East Coast schools for their "easy" rivalry games)