If you file in the US you would still need to report all income sources in Canada as well. Double taxation avoidance only entitles you to deduct whatever you already paid in the US, not cherry pick what you file in what country.
I am only flying for fun but I do a lot of consulting work in the US and Canada for the past 20 years, so here is my data point:
- When I work on a temporary basis in the US and I am paid by a Canadian company for that work, I file in Canada only.
- When I work in the US and I am paid directly by a US company, I must file a tax report in the US. I claim the NAFTA treaty position so I do not have to pay any taxes in the US, but I am still under the obligation to file a tax report. It is a lot of complicated paperwork for the first year, but after that it is easy and I do it myself.
It looks to me that in the case of the OP, he is paid by a Canadian company and is not based in the US - only doing temporary stuff - so he should not bother with the IRS.