As someone who lives in the middle of the United States, shipping my body out to the closest ocean for burial and flying family out to witness my burial doesn't seem very practical.
I don't even know if that's possible. 3 miles is a long way, and bodies are squishy and... easy to separate, relative to a rock or bullet.
The speed you would need to get that far might be high enough for the force to tear off limbs or to shred the skin. The chances of you getting a permit after you put "might rain human limbs or remains on the beach" is very low.
You'd probably have better luck with little solar-powered, GPS-guided dinghys or kayaks that can go out 3 miles, drop the body and come back.