The density that the Wagner meter uses is the green density. You do not adjust this density as the wood dries. So, use the values in their book, unless the wood you are testing is abnormally high or low in density. In fact, it is the natural variability of density of the same species that causes some confusion with this pinless meter.
You must indeed get the wood to a low MC, thick or thin, for use in MN or just about any environment that is heated. The environment is around 30% RH which means 6.0% EMC. So, any lumber above 7.0% MC will dry a little bit more and with drying comes shrinking and possibly warp.
If nice and dry, then when summer comes, the wood will gain several percent lister, but because there is approximately a 1% delay before swelling begins when moisture is added, and because swelling tends to be less of an issue than shrinking, we are not too concerned. In my book, the ideal is 6.5 to 6.8% MC.
Note that a 36 F depression at 100 F is under 3% EMC, so your wood should be drying toward that value. If it is not drying, then either you MC is wrong or the DB and WB are wrong...stick a small, thin piece of wood in the kiln and then use the oven test to check its MC which will also be the EMC. The pinless meter will not work on a small piece. Also, the pinless meter tends to give a higher reading for thicker stock.