N registry
The use of N registrations IS somewhat limited in Canada. However, at CYBW, I know of at least 6 N registered aircraft, most light business jets, but also a kitplane and a Reno racer. The business jets are operated by individuals who found the paperwork requirements of CAR 604 way too demanding. One told me it cost around $70,000 a year, and a 500+ page manual for a self-flown Citation. The kitplane is owned by a guy who doesn't like Transport Canada to an absurd degree. Quite often the airlines will lease in an aircraft and leave it on the N reg (or whatever country). WestJet did that with Delta 737-800s before buying their own.
A N reg. aircraft can be flown in Canada by any pilot whose licence would permit them to fly that aircraft type if it was Canadian registered. However, usually not in any other countries airspace unless they hold an American licence. So, while staying in Canada, a Canadian PPL or RPP would suffice to fly a Rallye.
It is my understanding that the aircraft is to return to the US during the year, but I am not sure of the amount of time.
While running maintenance can be done by an AME, the annual inspection would also have to be done by an American IA, rare in Canada, or a FAR 145 approved shop (expensive). However, there is a shop at Cutbank, about an 1.5 hour flight south of Black Diamond.
I haven't been on slack, I assume the aircraft is a Remorquer or 235 hp Rallye. The lower powered Rallyes are certified in Canada, & leaving it on the N reg would simplify importing it. Customs would be very interested in any such manoeuvre, but TC is fairly hands-off.