Why is large voltage drop a problem if within nameplate rating on motor?
If the inrush or starting current if not sufficient it will ruin your motor. This is not just opinion I am a professional electrician. The rated 230V current for a 2 hp motor is 12 amps. Code requires the book value to be used not the nameplate. I would use a minimum of 300% starting current some motors need up to 500% for short duration's.  without the increase in wire size the motor will brown out as stated earlier.  I just ran the numbers 300% x 12 amps at 230V for 400' is actually 1/0 aluminum with a 2.6% voltage drop. If you use 208V the FLA is 13.2. Do what you want ignore the Manufacturer and My advice that provides similar information, Just don't cry when you let the magic smoke out of the motor.