Missoula to Fergus Falls, MN best bike routes?

[livewombat]

40-50 European and American cyclists in velomobiles (2-wheeled, fully-faired human-powered vehicles) on a cross-country tour from Portland to Washington D.C. in July and August.  http://www.rolloveramerica.eu/

They are working on their route selection.  Distances will average 120 miles a day.  Arrival in Missoula is planned for the evening of August 2, with a one-day rest there, before leaving for Minneapolis on August 3. 

Are there traffic warnings for any of the likely routes?  Detours or construction?  Bad rumble strips? (the 3-wheelers could have problems with very narrow shoulder areas to the right of rumble strips)

Is Highway 12, 200, or 2 a more viable route across Montana?