I agree $10 is within the lower limits on a North American tour. I'm a middle-aged guy with a credit card and while I try to be somewhat frugal, my typical costs in the US are closer to $750/month, over double your goal. I spend nearly $10 on food alone every day. It's hard to get bargains in the places you may need to shop. You'll be stocking up in tourist towns approaching the National and Provincial Parks, for instance.

If you haven't toured before, you may not have experienced the calorie deficit from cycling in mountainous terrain, and the allure of $20 pizza in a tourist town where the beers are $7 (I just visited Banff on a hiking trip this fall).

Sure, there will be weeks in the heartland where you can get by on a few dollars a day, never step under a roof, etc. But as mentioned above, one day in the city can cost hundreds.

I met a crazy guy who'd been living on his bike for five years, 8000 miles per year, at a cost of $5000/year. It's hard to imagine more frugal than that (that's serious dumpster-diving freeganism), and that's well over $10/day.