Lot size is an over-rated criteria in the judgment of a lake lot. All lots in Northern Wisconsin are at least 20,000 square feet and many are close to an acre which is plenty of room to fit a house and a very large yard (a football field including the end zones is .83 acres).
Setting is more important than acreage. A five acre lot with 1000 feet of frontage could be less private than a half acre lot with 100 feet of frontage. To really judge whether a lot is the right size for you, you almost have to go out and stand on it. Look at where the nearest buildings are, not how close the nearest rode is. Note how busy the road is. Note how busy that part of the lake is with activity.
It's also important to know how much of the land is usable. There are many wetlands in Northern Wisconsin that can't be touched or even looked at sideways without the DNR chasing you down with guns blazing. Wetlands reduce the amount of usable acreage of a lot. If you are looking to add a large outbuilding to go with your house, you should make sure you have adequate room to build, otherwise the lot size number usually isn't as important as the feel.