How do I determine the maximum thrust that a Tesla powertrain (P100D for example) could produce if attached to a single propeller?
For a propeller/rotor, net consumed power = torque * rpm. For an electric drivetrain, net power delivered = current * voltage, with current equating to torque and voltage to rpm. Tesla should have really good data analyses on the power delivery as a function of demand over time, with wheel torque and wheel rpm as parameters.

Then you only have to replace the propellant medium: slippery air instead of the stony fixed world. Torque is a measure of drag of the rotor blade, thrust is a measure of lift. Both are a function of rpm as well, usually the rpm is limited by the tip speed approaching the speed os sound and is chosen to be as close as possible to it.

So a design process might be:


Determine payload.
Determine approximate disk load by comparing with existing designs, resulting in the disk area and the blade radius.
Compute rpm so that tip speed is about Mach 0.8
Compute power, torque and thrust from data available for comparable comfigurations.


Two books that contain chapters on pre-design of helicopters are Helicopter Performance, Stability and Control by Raymond Prouty, and Helicopter Aerodynamics by J. Gordon Leishman.

But the area that will give you most headache won't be computing the thrust etc, it will be figuring out how to control the flight path. Do you plan to use a swash plate?