Spokane to Calgary with heavy load - best way?

[rockchuk]

Hello, this is my 1st post and I really appreciate your feedback on the best route to take from Spokane to Calgary. I am underpowered and overloaded (Toyota T100 pulling a 20' travel trailer full of paintings and frames). I know the most direct route is via Sandpoint ID through Cranbrook on Hwy 3. I know most of that is 2 lane hwy, but the mountains concern me as I really have to gear down and take my time. Will I be holding up traffic causing safety issues or are there plenty of passing lanes?

I've been told I should stick with interstate 90 east to 15 north through Idaho and enter Canada through Sweetgrass MT. But that's an extra 285 miles! However, if it's a lot easier and less stressful I would be tempted to go that route. Getting there in one piece is what's required. 🙂

What is your experience on this? Your feedback is really appreciated....thank you!
RC

[n7bsn]

I-90 to I-15 more grades, 4th of July , Lookout, etc
Your other route has fewer

Be advised, if the Canadian border folk think you're unsafely overloaded
they can refuse you entry