So it's obvious that the Illini's equipment manager doesn't hold up the helmet like this guy does but just lays the helmet on the desk.
I think this explanation for the issue is overrated.
Look at the helmet on the right. If you rotated the I properly, it would overlap with the buckle for the chinstrap, unless you pushed it absurdly far back on the helmet, and even then it would probably cover that back hole in the helmet.
That helmet style is the one I most frequently see, not sure I'm familiar with the one on the left. Looks like the decal could fit properly there.
But if that other helmet style is going to be in the rotation, you've got two options: make the I smaller
Or, use a logo that doesn't extend so far to its lower corners
You know where I stand