What you will end up doing is planning a route, and if the weather is
good, flying it. But if the weather is low along THAT route, you will
probably be able to go on some other route. So plan on being flexible.
The air in Canada and Alaska is the same as anywhere else, so if you
can fly in Europe, you can fly Canada/Alaska too. Few people bother
with IFR/IMC because if it is cloudy, it's likely to be icy. There are
plenty of mountains in Canada and Alaska, just make sure you don't run
into one! You won't if you stay out of the clouds. The highways follow
the lowlands (with a few exceptions), so most routes can be done
avoiding high mountains. There is a HUGE mountain in Alaska, have fun
flying around it!