Just got off the phone with one of the US Bilstein engineers, and they figured out the issue. Looks like Bilstein did not redesign the European coilover for the US Smarts!!!! They basically sent over the European kit! duh!!

When asked if they had plans to redesign the kit for the US market, I was told that if they do, it would be a minimum of 2-3 months.
I guess I will go look at the KW's now. I had preferred the Bilsteins because they can lower the car an additional 1/2", but KW's are great coilovers, too. I'm going to call KW now to see if they have test fitted their kits on the US Smarts.
Edit: just got off the phone with KW, who said they did redesign the coilover for the US market - but then again, that's what Bilstein told me a while back, too - so we'll see. The shop I'm going through knows KW's owner, so he will try to confirm fitment with him. I'll keep everyone posted.