It's wonderful that you are here. It's almost impossible to find someone who knows someone who knew the family, especially nearly 50 years later.
Can you remember what your mom talked about in relation to Lucie? Lucie wouldn't have been any different than thousands of other young people all over Canada who were ready to spread their wings and discover their country or America and Europe. Like I said in posts regarding the Sumter Does, it was a rite of passage to decide to travel to the west coast, maybe by car or rail or even hitchhiking. It was the norm then.
Do you know whether Lucie's parents ever had any contact with her after she left home? Back then, if you said you were on your way to Vancouver your parents and friends never expected to hear from you until you arrived. And depending on the mode of transport several weeks could go by before someone was concerned.
I know people who stopped in Banff for a week or so, hung out in Golden, or ended up traveling through the northern states, especially if they were hitchhiking and just went the way the wind blew them.
I don't know if you are aware that Lucie has been ruled out as a match to many unidentified Jane Does across Canada and the US.