I'm a Canadian who has done several when I am down in the US.
Never had an issue. But I always just get paid via Paypal, and add the amounts to my excel sheet for taxes.
Technically you won't owe taxes, since you need to earn over $12,000 in Canada to start paying taxes.
It may make more sense to find Canadian based MSC since they have more options I find.
Fill it out, get paid, move on.