Yes it's been done. Slog is a nice understatement. Trout 'creek' will have you thinking how easy Pikes was

One note, please consider and don't take it defensively: Your flag that you left on the Thelon may bring you joy, for everyone after that would have seen it, it's garbage. Another example, you'll see on Great Slave lake, is places people have scrubbed lichen off rocks/ cliffs so they could mark their names. Not cool, it's graffiti. Instead of wilderness, thoughts of past travelers and an opportunity to pretend you're one more explorer in a remote and still pristine (ish) wilderness you get graffiti and garbage on GSL. Just think about it, as your paddling on that beautiful if rather intimidating lake. Or did you see the disgusting mess of Tom's Camp on Whitefish, on that beautiful esker? If yes, wouldn't it have been appealing camping, but the appeal taken away by that awful mess of someone who got to live the dream and then leave a mess for anyone else who would have like to enjoy the place? Yes the NWT and Nunavut are still remote, pricey and hard to get to, but the people who do make it there want to see the same wilderness you did. Please, please, please, practice no trace camping and traveling so the next person can have same amazing experience you did. Two of us in one canoe did paddle from Yellowknife to Baker Lake, connecting Trout Creek to Sandy Lake to Whitefish and Thelon. You will find no trace of our passage. The best route sounds like connecting thru Hanbury :p Trout creek is what you see on Google Earth, some shallow tundra puddles, water flowing under boulders between them, and no trails. I would say there is no 'one' route. Find the puddles on Google Earth and maps. Then how you go about connecting the puddles really depends on what you find, whether or not you are experienced with hiking and efficient at portages. There is often more then one strategy to make the route work. We much preferred hiking to repeated loads and unloads and are very experienced with hiking in difficult terrain using gps and mental maps. Another group, Paddles and Paws, I think made the trip work buy sticking close to and making max use of the water. They traveled from Pikes to Baker Lake. So the route does go and yes it is A LOT of portaging. Also, where is double barrel lake? Does it go by another name (beewick?) Have fun