The hydrodynamics plugin is used to simulate the buoyancy of the object it has nothing to do with drag and the aerodynamics plugin. And to calculate drag on a propeller atleast for planes each blade is considered as a flat box at a certain angle. So I think for the propellers of the T200 we have to consider each blade as a flat box and figure out the angle which had the most impact on thrust I am guessing that will be the angle near the center of the blade. I took a look at the iris drone's parameters and they used the following settings
<cp>-0.084 0 0</cp>
<forward>0 1 0</forward>
<upward>0 0 1</upward>
So in our case the air density will be the same. water density is 1000 and for some reason they are using water density for the drone so I guess we can do the same. And they probably got better results with 1.2041 which is a bit more dense than water.
The forward and upward directions are just the directions of force that needs to be applied so we can ignore that..Similarly cp and area. can be ignored. I can figure them out.
I don't know how to figure out the rest. I though the stall parameters can be ignored but they have -0.025 for cla_stall so I am not sure about it.