Wind profiling with APM

Hey Folks,
I am developing a project to measure wind profiles with a drone. I am currently using APM 2.6.
My initial idea was to have a quadcopter drift in the wind in alt hold mode, and get the wind speed/direction from the gps position. There are a few disadvantages in the precision and time needed to get accurate results.
An alternative could be to use loiter mode and calculate the wind from the average accelerometer tilt angles?

Can you think of ideas or parameters that could be easier/more accurate?
Does the APM have an internal error term for position hold that would be related to wind?
Better alternative than a quadcopter? (I would like to go to ~500meters altitude)
Any similar projects that I could learn from?

Any help will be much appreciated!