RE: Salt blocks and mineral blocks?
I know that is not legal in IL, but a man that I used to work with put a bag of sugar out on top of a hill twice a year. The deer tear this stuff up. I don't know if the deer would use it year round, but I don't see why not. It would appeal to the deer's sweet tooth. I have heard of using the kind of mollasses that you give to cattle. Put it in some old pantyhose and hang it from a branch, so it drips. If its legal, it would be worth a try.
Good luck.