Bayou_Boy- welcome to the forum, sounds like you have friends in great places. You should have a blast out in MT.
Since you've been fishing for saltwater stuff and largemouth bass already you are off to a good start and have the casting mechanics down.
Your buddies can recommend flies and all the other gear you might need. Probably the 2 biggest challenges for a fly fisher coming from the salt and/or fishing slower water for freshwater bass who wants to chase trout in streams will be "reading the water" to figure out where trout might be holding and "mending" your fly line after the cast to get a drag free drift-- something that can be tough to do when you cast across several different current speeds on a stream.
Here are some links to 2 great articles:
reading water: Reading the Water | MidCurrent
mending: A Mending Primer | MidCurrent
Next time you're out on the water, try casting a popper or something you can easily see in or on the water to a current seam between some slower moving and faster moving water and try throwing a mend or two to let it drift along at the same speed as other stuff floating in the water next to it. You can even do this in the salt by throwing and mending into some tidal current. It'll give you a chance to practice a little bit before you head out into the mountains in GA or out to MT.