Does the radar paint an image of a 3/4 submerged container? I understand that some 10,000 of them (yes!) are lost from container ships each year.
And I bet they drift well away from the shipping lanes.
If you collide with a ship there is at last a chance that someone on the ship notices, but with a container .... it's adios, baby
Pretty well, yes, and the odds of seeing one awash at night, even with two people on watch, are very poor.
There's two options: a steel boat with a stem thicker and stronger than a container (difficult, but a real argument for a collision bulkhead plus using limber hole plugs underway!); and/or forward-looking sonar with a proximity alarm and a range useful enough to wake you to see whether it's a whale sleeping on the surface or a container full of plush toys from China.
Personally, if I have to be sunk...