The tallest single continuous hill that I recall climbing in one day was Going to the Sun Road, east to west, about 2,000 feet of elevation gain between breakfast and lunch, that day also had the downhill of 3,400 feet on the other side. (I looked at my GPS elevation data for those numbers.) And I had enough time that day to take lots of photos too. I could have done west to east in the same day, but would have enjoyed it less. My point is that a lot of elevation can be done in a day. Mapquest tells me that your trip is roughly 600 miles. I am guessing you are looking at a trip of a couple weeks or maybe a bit longer if you do a more relaxed pace.

I use the drops on drop bars when I push into the wind, but a lot of people sit more upright and catch more air in a headwind. How you ride into a headwind is also a factor to consider.

Bike touring, if I anticipate a head wind I often try to roll out of the campsite around 7 to 7:30am, generically winds often pickup around 9 to 9:30 and peak around 2pm but that is my generic assumption for North America, it could vary locally where you would be. Are you an early riser or late?

Off the map, I picked Kamloops airport as roughly a midpoint on your trip for weather data. At that location it looks like you are just as likely to have a south wind as a west wind. Maybe the wind is not as bad as you anticipate?
https://weatherspark.com/y/145304/Av...ada-Year-Round

If your home is Vancouver and you would take a train or fly to Calgary if you started there, there is an advantage to riding towards home. Timetable is more flexible when you do not have to arrive somewhere to make a scheduled flight or train. And when your trip ends at home, you do not then have to pack for transporting your bike and luggage at the end of the trip.

Whichever option you decide, have a great trip.