Hey, All, we just got back from a week at Mt. Baker and exploring all the roads forthwith. I'd like to tag along.
Hudson, may I offer up a small deviation to your route that won't add much time?
Just outside Acme, turn right off of Hwy. 9 onto Mosquito Lake Road. It winds and twists and ends up on Hwy. 542. If you turn right onto 542, it'll take you to the Sumas crossing via 547. For a real treat, continue on 542 east to Maple Falls via LOTS of twisties. At Maple Falls, take Silver Lake Road to Sumas. Both these routes together would add about 20 minutes to the ride but you'll not get bored.
Either way, I HIGHLY recommend following 542 to 547 via Kendall, NOT Hwy.9/542 via Deming and Nooksack. Boring, stinky, dirty farm roads.
The last week in that area has been really nice. It rained a day or two and snowed in the higher elevations.
Remember your passport!