Living in SW British Columbia, I might intrude with some suggestions.
Your return map looks like you plan to overnight at Hope, and then head up the Coquihalla ( Highway 5) to Merritt. This is a 4-lane main highway.
An alternative would Highway 3 from Hope to Princeton--much less traffic, and more twisties, with passing lanes on most of the grades. From Princeton to Merritt to Kamloops on 5 A is also a lot of fun.
This goes from West Coast rain forest to lakes to open ranching country.
This would put you on Highway 1 to Banff, which has traffic.