I have found that fish in high alpine lakes often are not too choosy, since they have a limited amount of time to eat. A lightweight or ultralight spinning rod/reel with 2-4 lb test line is ideal: you can use lures or fish with flies and a cast-a-bubble. Last year, I had a 50 fish day in a lake in Rocky Mountain National Park using ultralight spoons behind a bubble, and hopper-dropper combos sometimes resulted in two fish on at the same time. The fish couldn’t resist, and nearly every cast caught a fish for a period of time. It was amazing.
I carry a few Mepps spinners, some Rooster Tails, some small Daredevil spoons, and a couple of Thomas Bouyants. The ultralight spoons were from Finesse Fishing; he imports things that you can’t find anywhere else in the U.S. You can still use your favorite flies tied on some light leader behind the bubble. Cast-a-bubbles can be filled with water to add weight and help you get the fly out to the fish.
Of course, sometimes the fish don’t bite at all. But that won’t happen to you. Have fun!