NOTE: I am not an expert on WI knife laws. I am only communicating what I've heard and what I think is common sense and proper etiquette for a knife owner/user.
Being in Wisconsin and buying a knife with a blade measuring 5"-7" is no problem. I can think of a few places where I could go right in SE WI and buy a multitude of knives with baldes in that size range and larger, and there would be no questions asked. I have purchased locally, and through the internet, a number of knives that have 5" blades and beyond. I thing the largest sheath knife I have in my possesion has a 12" blade. Owning any sort of knife or sword usually is not a problem in WI
Carrying is another story. A lot of municipalities have a 3" blade limit, from what I've heard. Does this mean you'll be breaking the law carrying something like a Spyderco Endura? Perhaps, but law enforcement usually has better things to do than set up check points at municipal borders to look for illegal knife blade lengths.
The only time I see possession being an issue is if you get into trouble. If you are a law-abiding citizen, you should have no problems. Do realize that the majority of the public fear all knives and view anything outside the kitchen as a weapon. There is no need to be unnecessarily flashy with a blade in public, be it on the job or wherever. You can show off your collection at home or in an appropriate setting like a knife show or at deer camp. If you must carry, stay out of trouble and don't attract attention to your knife, and you should be fine.
I do a lot of camping in WI State Parks. It is not unusual to see folks with with knives here and there in campgrounds. When visiting primitive campgrounds, I usually see younger folks wearing some sort of smaller fixed blade. If you are going to do this, be careful and keep your demeanor in check. The knife shouldn't be a problem unless someone feels threatened. I usually keep my knife or knives in my pack, and only bring them out when needed, regardless if I am car camping or packing in somewhere.
Finally, don't keep a large knife under the seat of your car. If you get into an accident, or your car is searched be LE for some reason, they'll find it and question its location. When transporting a knife, I have it covered in the hatch area of my vehicle or stowed below the rear cargo compartment deck.