The problem with this is that we have no way of measuring the speed of an incoming train before an attempt. If the train looks like its going fast then it probably is. I came up with the idea of just sticking my head out infront of the train to reduce risk (well got the idea from someone else). Surely this applies to the whole body as well which may or may not answer your question but here, i took this from a reddit post.
"Trains have an operating speed of 150 mph most of them weigh between 100 and 200 tons. The force transfered from the train and to your head would certainly exceed the 520 pound of force the skull can endure."
If the skull the strongest bone in your body cant endure that then i doubt the rest of your body could. I customized my way of doing it alittle but hopefully it works as planned. Anyway i hope that helped some.