I'm flying a payload (bait dropper) on my MP which blocks the downward ultrasonic sensors.  I have turned off these sensors prior to flying.  Will my MP crash or somehow error if I automate RTH landing?  My goal is to drop the bait, hit the RTH button, and then be able to focus on my fishing rod while the drone lands on its own.

Hi, Thanks for the inquiry. This process would be risky for the drone and might not detect any object while flying. Please use your aircraft in a recommended usage. Thank you for the understanding.

Yes it will rth with the sensors turned off but i would recommend stopping the rth on its way down and hand catching as its landing this will avoid any hard landings
The sensors are designed to calculate the drones distance from the ground during landing the drone can then slow its descent for a soft landing.
With The sensors turned of it cannot do this and a hard landing usually happens.

Hellsgate is right on this with the sensors off or covered up.  Suppose you had a problem prior to dropping the payload........the MP ain't cheap.