Like you know, I went off your design. Changed the outside of the bumper but kept the winch plate and mounting pretty much the same.
Here is a little FEA analysis I did on my free time. This is for a 10,000 lb pull.
The red zone indicates a displacement of .030". Which is very little.
In the strain plot using a36 steel, the bumper seems to hold up at the mounting holes. There is one red spot that goes over the yield strength, but I believe that's an issue with the meshing.
Anyways, when I get some more free time I'll keep playing with it.
Its good to hear that the winching has been going well as theres only so much computer can tell me lol.
I have the bumper done but it no winch on it yet.