I am also in Mn about the same situation as you, 140 acre lake no access. I have contacted many of our “wonderful” agencies and surprise surprise I could stalk walleyes in the lake with a permit. I had to contact the fisheries division in my area to see if he would sign off on the permit to stalk and they would. Now there is some paperwork involved but it is possible to do. Like one rule is the walleyes have to be from the same strain that your lake is. But I did find out that there are private people in the state that sell fry or fingerlings that don’t like doing paperwork😉