Haven't been in the Knife area lately, but I scouted around Sawbill this last weekend. Not sure how much this may have changed with the storm yesterday...
I didn't make a hole in the ice but someone I talked to said it was about 24" thick. That "felt" about right to me as I walked on it. It appears to be frozen rain over frozen slush, bare ice over most of the lake. Rough, but very slippery to walk on, micro spikes would have been best. I'm not sure skis would have worked very well. But a layer of fresh snow on top would fix that.
Along shore there was a thin layer of crunchy, grippy snow that was perfect for walking. I easily walked from the Sawbill put-in to the Alton portage in just light hiking boots.
Anywhere near moving water, even small trickling creek mouths or seepages that aren't shown on the maps had thin ice and some open water.
The snow in the woods was very crusty and hard, I was able to stay on top of it for the most part in my hiking boots, but some small synthetic snowshoes with crampons would have been ideal.