I'm not familiar with anything that'll work by phone- usually they would require a wifi connection so it would need to be in wifi range of your house and even in that case, all the ones I've used have enough of a lag that they wouldn't work for that purpose. You can look into this product:
swifthitch.com
Its intended for hooking up to a trailer but can be used for a plow also

Swift Hitch Camera Systems - Trailer Hitch Camera, Back-up Assistant Camera
Swift Hitch is well recognized brands in RV, Trailer, Farming Equipment Industries. Sold thousands of camera units to satisfied customers in USA and other countries.

Its intended for hooking up to a trailer but can be used for a plow also