Re: Bozeman, MT help.
Gallatin head west on main street to four corners then head south (left) first access should be few minutes on your right clearly marked. Parking might be tuff with a trailer, but the fish are there. I would stop at a fly shop in town or call for a report and or check flows. Sounds like west and mid west MT, are starting runoff already.
I have fished there a few times when in a hurry. Few deep pools right at the bridge but worth walking up a mile or two and fish it all.