Thanks for the suggestions.
Flathead glacier transport will pick me up in Roosville, w/ 3 or 4 day notice, and take me to Kalispell airport for ~$130 USD.
I found a rental from Kalispell airport to Butte, one way for $143 including taxes etc. 2nd to smallest car. Base rate $119 and available.
I found some stuff before I checked here again and came to the same conclusion as indifabz, ride to Whitefish and take the bus to Butte. Around $50 and 6 hours or so. After the time on the trail/road it'll be good to catch some zzzz's before the 1000 mile drive back to Albq. The only caveat is you have to have your bike boxed to get it on the bus. I called Glacier Cyclery (http://glaciercyclery.com/
) and they said it would be no problem to get a box from them. In fact, they said if they're closed, just go out back and get one off the pile. They're just a couple of blocks from the train/bus station.There's bus service south every day around 11 or so.
After all the planning to do the ride itself, it was really nice to find the tail end not too bad to take care of.
Thanks for all your help,