DOOOD! Now, you're speaking my language!:
WALLEYE:
This is a very mild, delicate, non-oily fish that gets good meat texture when it is cooked. If you do anything too fancy with it - you'll just wreck it.
I like to beat an egg and some half-and-half, flop the fish into this, then into Ritz cracker crumbs, corn meal, panko, or a mix of all three, and pan-fry in (preferrably, lard or oil with a little bacon grease) until golden brown. Salt & pepper to taste.
Fresh Walleye from cold water is a real treat. Serve with a little tarter sauce.
Serve with fried potatos (get some baby yukons or russets, boil them the night before), then slice and fry with a little onion & butter.
I like pan-fried Walleye with some eggs & toast for breakfast, when I get the chance!
NORTHERNS:
If they're largish, fillet them and remove the ridge of "Y-bones" that run along the lateral line of the fish. (You end-up with two fillets per side - any experienced Northerner / guide should be able to show you how to do this.) Then, fry in the same manner as Walleye.
For smaller ones - look for a recipe to "pickle" them. In this case, you can leave the Y-bones in, since the vinegar will dissolve / soften them.
LAKE TROUT:
This fish is very fatty. We like then two ways:
baked - gut & gill a medium-size fish (up to 5 lbs), then score the skin, salt & pepper inside & out, stuff the body cavity with peeled small onions & stitch-up. Brush with a light coat of oil & bake at about 350°F.
(I would use a roaster-rack, so that the fat can drip-off and collect.) Warning - this method can make a kitchen stinky!
Boiled - Lake Trout makes EXCELLENT fish-boil:
-Put a big kettle nearly full of water, with an inner basket outdoors, on top of an open wood fire or gas (turkey-fryer).
-Get the water to a rolling boil.
-Add quartered potatos, chunks of big roaster carrots, and halved onions to the water, with salt and pepper.
-Give it about half an hour at a moderate boul before adding the fish
-Steak the fish and add it to the boiling mixture. Give it about 20 minutes at a gentle boil.
-Either skim the fat / oil off the top, or toss some gasoline on the fire to cause a flash-boil, that will cause the kettle to boil-over, taking most of the fat/oil with it.
-Enjoy
(For dessert - some nice tart cherry pie works perfect)
Lake Trout can also be slow-cooked, indirectly, so that a lot of the oil will cook out of them.
In my opinion, when cold-smoked, they get too soft and oily (although the Canadian ones are supposedly less-so than the ones that we catch out of Lake Michigan.)
NOTE - IDENTIFICATION:
If you are using a guide / resort-keeper, they should be able to inform you about the limits on what you can transport home. For fish that you plan to take home, you'll usually need to leave a tag of skin / scales still attached, for identification by border security.
Hope you enjoy your trip - I for one am jealous.