One thing you might want to do is buy the DeLorme Atlases for MT and ID, cut out the appropriate pages and carry them with you. They're helpful for making the "as you go" decisions based on fire closures, etc. They have GPS grids in case you really get lost, have a GPS, and get off the Ley maps (not all that hard to do in places). It's a good exercise to pencil in the route(s) from the Ley maps onto the DeLorme pages. State road maps might help with bailouts and end-of-hike decisions.
The only mail drop I did in MT was Benchmark. Ditto the ETA info, and call from East Glacier when you have an exact day. I did another at Brooks Lake Lodge in WY.