There was a Chinese general who supposedly did something like that using a firehose.
But the point of the whole thing is actually to spend time learning and researching your family history. In other words, the literal posthumous baptism is not the point. That's the ritual. It's what to learn and do along the way of accomplishing the ritual that is the point.
Note: in Mormon theology, those that die and receive their baptism by proxy still get to choose to accept or reject that baptism in the afterlife.
This always struck me as one of the most stupid and illogical tenets as it's in opposition to the concept of loving and just God: why create millions of people who have no chance to meet the Gospel, and then automatically condemn them to suffer forever, just like that, for nothing? It really makes no any sense! And yet, the modern world lives on remnants of these ideas.