Agree with seeing Salmon Glacier. You won't need a 4x4, just a desire to drive on some gravel roads.
And as I like to tell my friends about the legal border crossings without any border agents -or is that illegal border crossings?: Cross into the US - Hyder - no agent, then Canada on the Salmon Glacier road - no agent , then the US - Hyder - no agent. But then the Canadian agent going back to Stewart asked where we were going and I replied back to the CG. "OK, have a nice day". I think he felt obligated to ask us something. And we did have our passports.