Don't lie. If caught you are going to be inadmissible not just this time but more likely for years to come and face additional scrutiny on future visits.

Your employer should be providing legal assistance as to whether you work is covered by NAFTA (visa free) or whether you need to apply for a visa. Bring a copy of the sales agreement and Canadian client contact if work is covered under NAFTA.

If this will be recurring travel, you may want to enroll in NEXUS.