We crossed at Sumas, spent a night at Hope - neat little town with large wood carvings along the street and even a Japanese Garden. Stocked with food and exchange some money and the drive up 97 was very pleasant - don't recall a big climb.
You're not going to have mountains like you would have in Colorado if that's what you're worried about. Millions of RVers have driven to Alaska in all kinds of RVs - some even before the roads were paved. :) You'll do just fine.
Move over the Alaska/Canada section of this forum and you'll find lots of additional good information.