What are typical ketone levels during an extended fast?

What are the typical ketone levels that can be expected during an extended fast, after ketosis has begun? For example mine has been 40 mg/dL, as measured on a Rapid Response 10-parameter reagent strip. A couple of Internet sources say that this level is in the "moderate" range: https://www.nlm.nih.gov/medlineplus/ency/article/003585.htm
and http://www.isletsofhope.com/diabetes/care/ketones_1.html

Of course we are not speaking of the dangerous diabetic case when both ketone bodies and glucose are present. What has been your experience?

I have heard that a high level of ketosis may not necessarily burn more fat but that it is not harmful either. What could be the danger in a high level of ketosis?

I also wonder if a drop in ketone level might signal when to end a fast before starvation begins, when all available fat has been scavenged. The other clear signals to end a fast are said to be the return of true hunger and a clean tongue. I have not reached that point yet (Day 19 today, present weight 110 lbs down from 132, BMI 17.8) but will report on this later.