I remember reading somewhere (and I can't for the life of me remember where) that turkeys really are not considered to have a carrying capacity on their habitat, at least for all practical purposes. They are birds and birds normally don't impact the carrying capapcity of the land with their population. They just have too many options to feed on.
Not sure about this, there is only so much food above the ice. For example the box elder seeds on most trees are stripped off. A favorite turkey food to be sure but when a large flock gets to those trees each turkey gets few; whereas if there were fewer turkeys there would be more seeds per turkey. The food options are limited here.
Sure would be nice if the WDNR would do more basic research regarding carrying capacity for turkeys. You are right about their current management strategy; it is all about the tags after looking at the sales and harvest. That is like driving while looking only in your rear view mirror.
If I am not mistaken turkeys were historically common in this area WI- from the south half of 4 continuing to the south and east. Northern 4 and up is probably pushing the range a bit during hard winters. I would think that is where carrying capacity would matter.