The magnetic stove thermometers are nice also in that you can move them around and you will find significant differences at different surface points on the side, front, top, etc. Doesn't really answer your question about how hot to burn, but it's interesting to see the differences.
As to how hot to run it, my Harman manual says the stovepipe temp should not exceed 500*, and as I recall it says how far from the outlet to take the reading. Harman doesn't say clearly, but I think they mean to measure with the magnetic surface thermometer because a few lines earlier they recommend having one. (A probe thermometer will likely read twice as high.) I have checked within six inches of the stove outlet, at moderately high burn rate, and it was about 400*.