The 7D is better, but not necessarily for the reasons you cited.
First, low light. The 7D is not a great performer here. It has two image processors whereas the 60D has only one, but I've never noticed a difference in noise levels at higher ISOs-- which is what you'll probably use for football. Since most high school games take place in the evening, and because you'll need a high shutter speed to freeze action, you'll be living above ISO 800 virtually all of the time, over ISO 1600 some of the time, and occasionally up to ISO 3200 if you're really in a pinch. Having owned a 60D and shot with a 7D, I wouldn't use ISO 6400 unless your final output will be pretty small; the noise is distracting by that point. ISO 3200 isn't stellar but can be cleaned up in post. ISO 1600 is the highest level at which I consider detail and noise acceptable without some involved post work. But to return to your original question, I think low light performance is a wash between the two cameras.
Ruggedness and build quality-- the 7D wins. If you're rough on gear, it might be worth upgrading. I believe the 7D also has a more durable shutter, which could matter if you're keeping the camera for several years. That said, the 60D's build quality is unfairly derided. It's not magnesium alloy, but its solid, has some weather sealing, and (unless you've been carting around 1-series bodies for years) never feels like a toy. I have a T2i, a 60D and a 5D Mark III, and the 60D handles more like its big brother than its littler sibling.
To me, the differentiating factor for you is probably autofocus. Before I upgraded to a 5D Mark III, I shot semi-professionally with 60D, and I found its autofocus perfectly adequate-- assuming your timing is decent and that you're comfortable moving around the focus point (easy to do without lowering the camera from your eyes) in situations when the camera's tracking algorithms aren't up to the task. The 7D's autofocus shares more DNA with the upmarket 5D Mark III and 1DX than it does with the 60D. For a sport like football, that could make a big difference.
Burst rate is another big one. The 60D does 5.6 frames per second whereas the 7D does 8 frames per second. I've found the 60D to be just fast enough for sports. But the "perfect moment" arrives and vanishes in an instant, so having 30% more frames for every burst is an advantage. If you do a lot of burst shooting, you should consider buffer as well-- pretty sure the 7D is better.
Unless one of the above comments sold you on the 7D, I think the 60D plus a solid lens might be a better option for your needs. Shooting in dim light at high ISOs and high shutter speeds demands a bright lens. The 18-135 is convenient in its range but deficient on the aperture requirement, especially at the tele end (which you'll probably use more). Speaking of the tel end, if you're shooting the action from the stands, 135mm might not be long enough for you. It's not exactly a budget lens, but a used 200mm f2.8 might be a good option. You might find one for $600 - $700, you'll get the effective reach of a 320mm lens, and you'll have the brightest aperture you can get at a tele length without paying a fortune. In you're shooting sports at night, 60D + 200mm f2.8 > 7D + 18-135mm, in my opinion.
That said, if can find a way to delay your decision until the end of the month, the 70D might solve all your problems. It will probably be a little more expensive than the 7D's current price, but I expect it to be better for your needs than either of the cameras you're considering. Hope this helps.
