Why is the LT3080 input voltage limited to 36V?
The part actually supports 40V, it says 0 to 36V because that is the voltage range that the specifications of the part will work. The part has been tested for 0 to 36V. 

The absolute maximum ratings are ratings for which the part will fail you can't go more than 40V relative to Vout



So you could do what you suggest if the voltage drop across a resistor was always more than 660V, thus keeping the voltage drop across the LT3080 under 40V.

Looks like it could work depending on the load: