Assuming that you are meeting the tire and tire chain requirements, that leaves
- allow enough schedule flexibility to sit out a storm, waiting for better weather, and
- stay low - there will much less probability of snow down on the Trans-Canada (Hwy 1) in the Fraser valley than up on the Coquihalla (Hwy 5).
The Yellowhead Pass is lower and easier than the other Rocky Mountain passes (Kicking Horse on the Trans-Canada, Crowsnest on Highway 3), but going from Vancouver to anywhere in southern Saskatchewan via Edmonton instead of via Calgary or further south is a big detour.
The other option, of course, is to have Escape store your trailer until spring, if they'll hold onto it that long.