I spent three days on Rog Lake - South and west off the end of the Gunflint Trail. This is suppose to be a brook trout lake that has been planted many years in a row. Using a depth finder, I was able to mark fish down at 40-50 feet but never had any bites in 3 days. All we caught were bass along the shorelines. If you haven't already, I'd suggest calling one of the state DNR offices and request the pamphlet "Lakes Managed for Stream Trout" or something similar to that. It lists all the lakes in Minnesota that are planted with trout. If anyone has any suggestions on any of these lakes in St. Louis County or the Arrowhead region, please let me know as I'd like to try my luck with trying to catch some Brook trout in lakes.
I've always had good luck for lake trout on Seagull Lake and Oyster Lake. Try deep diving rapalas or Mepps over deep holes up to 100 ft but keep in mind that they are usually higher in the water column. I have had days where they would bite at 50 ft to 20 ft off the surface, but usually over big holes. Might want to try Peter, Bat and Virgin a bit Northeast of Little Saganaga too.
One thing to consider - if your fishing really deep and you catch a lunker, you pretty much are going to have to kill it. Dragging them up from that depth into the warm surface water will really stress the fish out. The change in pressure and temp will make returning the fish a moot point.