For the Boundary Waters, check out the Paddle Planner map:
https://www.paddleplanner.com/tools/maps/bwcaqueticomap.aspx
If you zoom in, the partner outfitter (which is most of them) logos show up. Also, if you click on the 3-bar menu button on the top left of the map, you can turn on the motorized overlays, which is pretty much any large lake that's partially in and partially out of the Boundary Waters. Generally those lakes have outfitters who will ferry your crew, gear and canoes in via motorboat. However, that also makes them popular locations.
You do need a permit to camp overnight in the Boundary Waters. Permits became available the last Wednesday in January, so many have already been booked. Last year was a record year for visitation, so you'll need to check what's still available:
https://www.recreation.gov/permits/233396
A permit allows you to enter and camp overnight, with max group of 9 people and 4 boats. I believe you don't need a permit for day trips.
I haven't done a fly-in trip myself, but I know that
Canadian Border Outfitters on Moose Lake does fly-in outfitting, and I recommend them based on a trip I did departing from their docks.
Fenske Lake Cabins/Echo Trail Outfitters (north of Ely) is my favourite outfitter up there. No fly-in outfitting, but they are connected to enough lakes that you can do a small Boundary Waters-style trip without actually entering the Boundary Waters. You could also stay in their cabins and day trip across a few portages to fish. The cabins are nice, but there will be people in the other nearby cabins, as well as in the NF campground across the lake.
If you go up to Grand Marais on Lake Superior's North Shore, and then follow the Gunflint Trail to the Boundary Waters, Rockwood Lodge & Outfitters, Tuscarora Canoe Outfitters, and
Clearwater Outfitters are three I've used and recommend. Clearwater's historic lodge is something to see. If you're in that area, make sure to plan to stop for a meal at Trail Center Lodge on Poplar Lake.
Bottom line, you're going to have to work really hard to find true seclusion (i.e. not seeing another human for at least 1-2 days) in the Boundary Waters between mid May and Labor Day. However, it can still be a worthwhile experience if you don't get hung up on that. A silent wave to fellow canoeists passing by your campsite isn't the worst thing.
If you're not familiar with all of it, pick an outfitter and they can walk you through selecting a route, get permits, etc.
From what I hear, it's not realistic to expect to do any fishing in Canada this year. If it were, Ontario's Quetico Provincial Park borders the Boundary Waters and is roughly the same size. In normal years, you can book a fly-in trip to Quetico and paddle back to the outfitters docks. Not this year, though. If the border were open, you can cross freely if you get a Remote Area Border Crossing permit from Canada, but not this year. However, you are free to use the portages on the Canadian side of the border waters per the Jay Treaty of 1794. We did this our last trip up there, in 2019.
The area between the Boundary Waters, Grand Marias, and Grand Portage in MN can be relatively secluded, as not a lot of tourists make it past Grand Marais. There are State and National Forests in that area, as well as tribal lands and a National Monument. All have different rules. If you go to that area (instead of up the Gunflint), I recommend
Sawtooth Outfitters in Tofte, MN. Let them know the guy who put a gash in a brand new canoe 2 years ago on the Pigeon River sent you (I need to build some good will back with them!).
Finally, based on what you're describing, you may want to look at Isle Royale also. You have different rules and options there, too. It's technically part of Michigan, but much closer to MN and ON, with the shortest ferry ride leaving from Grand Portage. The Park Service called off the ferries for the year last year, but I haven't heard what the plan is this year. Northeastern MN was so busy last year, I can't imagine they can be shut down again.
Further west, as others have mentioned, any of the cabins or outfitters around International Falls, Baudette, or Warroad would be more than happy to set you up. Fishing trips are these guys' bread and butter, but most aren't anything like a wilderness trip.
Also, I just read that MN's Northwest Angle (MN's "chimney") is really suffering, as you have to drive through Canada to reach it by road, and you can't do that right now. If you can find a way to fly in there, I'm certain it would be uncommonly quiet this year.
