Both American and Canadian regulations do not allow you to fly in Canadian Airspace with BasicMed.

Overflights through Canadian airspace are also not allowed, regardless of who controls the airspace.  

> Section 61.113(i)(2)(iii) requires that the flight, including each portion of that flight, is **not carried out outside the United States**, unless authorized by the country in which the flight is conducted. Title 14 CFR part 1, § 1.1 defines the United States as the States, the District of Columbia, Puerto Rico, and the possessions, including the territorial waters, and the airspace of those areas. Thus, a pilot operating in the United States, as defined in § 1.1, may elect to use BasicMed.
Airmen certificated by the FAA are represented to the International Civil Aviation Organization (ICAO) as compliant with ICAO standards for private pilots, among other requirements. As BasicMed standards divert from ICAO requirements, flights must be geographically limited to operations within the United States, unless specifically authorized by the country in which the flight