Can't speak for Elk Lake as it's on my to-do list, but I fished a lot of largemouth in the Kootenays. Best trips were the hottest days of the year, 7 PM till Dark, fishing weedless top-waters or poppers on the edge of the weeds or right in them. Explosive strikes, Tons of fun! Largemouth will hit top-waters way more than the Smallies but get your lure right in the weeds and use heavy line as once they hit they like to head to bottom wrapping the line in the weeds as much as possible. Use a stiff rod and good line and horse them out.
Our best trip was landing and releasing 36 fish in three hours. Some were over 26 inches and 6 # plus! Kept enough for a couple of dinners and put the rest back. Good Times!
If I get down there this summer holidays I'll look you up and we'll hit'em hard.